It's been said many times that the Sumo would be sold by a Swiss brand at 2 or 3 times what Seiko charges. I thought I'd compare my blue Sumo with my Planet Ocean to see what, if anything, the extra $$$ gets. I understand the street price of the Sumo when released was approximately US$400, and the Planet Ocean was approximately US$2,000, so a more natural competitior for the Sumo would be a Bond Seamaster, but I don't have one of those.
Both the PO and Sumo are ISO certified dressy dive watches with automatic movements.
Although functionally similar, the PO is rated to 600 m, compared to 200 m for the Seiko. I have a theory that Seiko divers are actually engineered to go deeper than 200 m, but testing the WR at greater depths (for ISO) is time consuming and expensive. It is only a theory, but people have reported 200 m WR Seikos passing 400 m and (from memory) 600 or 700 m. Regardless, 200 m is more than enough for just about everybody.
The PO is fitted with a helium release valve, unlike the Sumo:
It's cool that the PO is suitable for professional use, but how many commercial divers would wear a PO down there? Personally I would prefer an automatic valve as fitted to the 16600, as the manual valve protrudes somewhat awkwardly from the case. However, the 'He' in relief is extremely cool IMO. There is an argument to be made against these valves as they present another entry point for water. I sort of agree, but as long as the watch is serviced regularly it shouldn't present a problem, especially at the depths most people are likely to reach.
Sapphire is fitted to the Omega as standard, compared to borosilicate glass on the Seiko. Mine has a Yobokies sapphire fitted, which ironically has a massive gouge in it. All my modern Hardlex divers are scratch free. Optically the double domed PO crystal is better than Yobokies' sapphire (less distortion and AR not as obvious), and probably a bit better than the standard Sumo crystal, too. The doubled sided AR on the PO is incredible, with the crystal literally disappearing much of the time. That said, the outer AR coating has many many hairline scratches. When I eventually get my PO serviced I'll replace the crystal with a later, internal AR only, crystal.
The Omega has a more refined and advanced movement, the 2500. It is based on the 2892, already an excellent movement, to which Omega has fitted a co-axial escapement (which supposedly extends servicing intervals) and a free sprung balance. The 2500 is also decorated with perlage, stripes, gold filled engraving, and nicely polished screws. It's a good looking movement.
The 6R15 is based on the 7Sxx calibres and as such is a less refined design. Most plates have a brushed finish, with stripes applied to the rotor.
The 6R15 is also a good looking movement, IMO, just not as detailed. The 6R15 winds smoothly but the 2500 is incredible, truly buttery. Smoother winding than my 16600 or SBGH001 even. You can barely feel any resistance or anything mechanical while winding it. I actually like the 'micro buzz' that is felt when winding any Seiko from a 6Rxx to 9Sxx, but the smoothness of the 2500 is worth noting. Crown and stem on both watches feel reasonably solid.
I'm not that concerned with accuracy but my experience with both of these movements has been very good. The 6R15 in my black Sumo is around 1-2 s/day. Not sure about the blue one, but seems to be under 10 s/day off. The PO seems to run 3-4 s/day.
Power reserve for the 2500 is 44-48 hours. 6R15s are known to run for 52 hours.
The casework of the Sumo is a highlight, and is more complex than most watches at that price point (lots of curves and interfaces between polished and brushed surfaces). The treatment of the lug ends, especially, is extremely complex and would require precision machining. My example is well used, but the complexity of the case and refinement of the finishing is still largely evident:
The PO case is also very impressive. The machining is on a par with the Sumo, IMO:
The PO polish doesn't appear as smooth, even, and deep as on the Sumo. Even on my beat-up example, the quality of the Sumo polish is evident and extremely impressive:
That mirror finish would not be out of place on a Marinemaster 300 or Grand Seiko.
The Sumo is often criticised for the fit of the bracelet endlinks. It's pretty good on this example, and also good on the PO:
Both crowns are signed. The Seiko is engraved, the Omega cast in relief. Engraving has the advantage of not wearing down over time with use and polishing. The Omega crown is superior functionally, however, as the small sharper 'serrations' are much easier to grip and manipulate than the Sumo's larger, smoother edged treatment:
Both cases have screw-down backs, but the Seiko is outclassed here. As much as I respect the heritage and tradition of the tsunami, it just can't compete with IMO the best dive watch caseback of all time, and one of the best casebacks on any watch:
The engraving on the PO caseback is also top notch:
The most often criticised aspect of the Sumo is the bracelet and clasp set-up. I actually think the bracelet is pretty good:
It's a one link design, styled to look like a five link. A three or five link would be preferrable, but this one is solid, smooth and quiet. Pretty much all you need in a bracelet. It looks good, too, when viewed in real life (i.e. not macro photographs). That it is generally considered a poor bracelet speaks volumes for how far dive watch quality has progressed.
The links themselves are nicely brushed and polished, and the whole thing fits together nicely. The PO bracelet takes things up a notch or two. It really is one of the niceest dive watch bracelets out there:
A simple three link design, it fits together very well and is silent and smooth as silk. It is beautifully brushed, and the polish of the link ends is also impressive (especially for a 3 year old watch):
The Sumo bracelet is nice enough, the PO bracelet is nice. But apart from the movements, the biggest difference between the two watches is clasp quality. Omega uses a clasp which appears to be almost entirely milled from solid steel:
This is a clasp which truly impresses with construction quality:
It looks and feels expensive, and no doubt is expensive. A stark comparison with the Sumo (and Monster, SKX007, et al) clasp:
And yet... the PO doesn't have any micro-adjustment on the clasp. A glaring ommision on an otherwise superb unit. The weather is warming up here, my wrist is expanding, and my spare links are packed away. Yesterday the PO was becoming uncomfortably tight, and until I unpack it won't be getting much more wrist time.
The dials and hands of both watches are very good but not exceptional. The upper hand surfaces are polished to a high standard, but the hand edges are unfinished. Lume application and general fit is good on both dials and hands:
Printing on the PO dial is possibly whiter (it looks like a thicker layer of ink may have been applied), but it is a close run thing. Lume on both watches is exceptional. Seiko wins here, due to greater lumed surface area, but both of these are close to a Monster in terms of glow brightness and duration.
The Sumo was manufactured in 2007, the Planet Ocean in 2008. It is obvious the Sumo has led a much harder life, but the refined finish of the Sumo does highlight hairlines and swirlies more than the less precise polish of the PO.
The bezel action of this Sumo is sloppy, loose, and imprecise. The bezel action of a new Sumo is one of the best I've tried so this one appears to be worn. With a new gasket and click spring at service it would likely be smooth and precise again. The PO bezel action is still as precise and mechanically clicky as I remember a new one to be, if a fraction hollow feeling.
Finally, the Mum test. I asked Mum which watch she thought looked most expensive. She pointed to the Omega with little hesitation, stating that the bracelet made the biggest difference, and that the Omega bezel looked finer.
In conclusion... even my mum can see that you get higher quality with the PO, overall, but it's a LOT more $$$. It is also worth considering that if both watches were on identical straps then the quality difference would be markedly reduced.