Welcome to The Three Musketeers of Doxa Sub models, all of which are Holy Grail pieces!
They are all the larger case size more catered to those like myself who have over 6.75 inch wrist, mine being 8.25 inches.
The 750T COSC Professional is the C2 Corvette 1967 427 engine with 450 bhp of the lot, a classic amongst the classics. Only 130 were ever made, 30 made available to the public via retailers. All sold out! This is probably one of the most desirable models and version!
The 1500T Professional is a great one as it is identical to the 5000T Professional with the same depth capacity 1500m/5000ft but the dial, batons and hands are of the same design as the traditional orange dial found in other models. Only 50 of these have been made and all sold out!
The 5000T COSC Professional at The Top of The Tree as it is as good as it gets. It is very rare to find it with the COSC movement. The standard non-certified chronometer model is no longer mentioned on Doxa Sub site and completely sold out. They were in limited numbers and I do not know how many were made in COSC. I am sure someone will be able to tell me!
All of them are in pristine condition (99+ % TZ rating) with everything that came with it apart from the CD/DVD which provided with my 300 T-Graph Professional with a sapphire bezel. The COSC certificates are in protected sleeves. The Sub tube for the 750T is larger than the others amazingly!
Feel free to let us know what you would consider to be the fourth Musketeer and provide details as well as photos.