Here's a quick update with my impressions of the watch and strap after 10 days with it.
I changed the spring bars to the lower of the 2 above. These I got from a well known Australian seller online. These are listed as 22mm pins and as can be seen, when compressed will give a tighter and more robust fit.
The isofrane is easily the best rubber strap I have had. It's much more comfortable than the Seiko straps. Softer rubber and micro adjustment get the perfect fit. I'll get another for the Tuna.
The watch itself is very nice. For the first week I wore 24/7 and it lost 28 secs so -4/day which is pretty good. I'm now wearing only during the day and leaving it face up on the table at night and it's now lost 8 secs in 3 days so just under -3/day. I'd say that's pretty good for a standard 2824.
It's the perfect size for my wrist, sits very flat, quite like the Submariner unlike the Tuna which wears tall.
I do however have one irritation and that is the orange hand! For others I'm sure it's fine but with my eyesight in dim light I lose the orange against the black so the minute hand becomes the same size as the hour hand! No problem at all in good light and then I really like the orange hand.
I will keep my eyes open for a whiteshark 750 however I think the easiest solution is to get the minute hand painted white to match the hour hand or try and get a white hand from Doxa.
Does anyone know if they would supply a white hand? Other than that and the previously mentioned bezel paint loss which doesn't bother me at all, I'm really pleased with this 750 and it's exactly what I was looking for. I don't think the Tuna or the Sub will get much wear after this