Help with Yachtmaster--> pics nside

[LuminousMaximus]

I have been lurking and tossing around which Rolex I would like, and am leaning toward the 40mm Yachtmaster however, I have seen many variations which are not in the Rolex website.

Some have ruby's and sapphires, others with diamonds, and even others with mother of pearl and yellow gold.

My question is should i simply purchase from one of our vendors and get the Rolex serviced from them or should I buy from an AD and pay the higher price so I can get it serviced from Rolex?

I mean to say I am worried that if something does fail in my rigorous activities and my Rolex needs parts, the former seller may not be able to acquire them correct?