Hey Sam308:
I have [many] and use a Casio G-Shock only on my dives. They are nearly indestructible, cheap, low profile, and if something tragic should happen to it, I'd give it a small going away ceremony and then bust out another one in memory and more importantly for serious duty. I wrote
this as an opinion for another SB Member asking about dive watches and even though I went link crazy, it said everything I wanted to about G-Shocks (and the video is pretty neat). Get one and be done with it.
On the other hand though, if you had an expensive watch model that had an image associated with diving, such as a Rolex, Tag Heuer, IWC, or Bulgari, I imagine (more likely I'd bet dollars to yummy donuts) that if you had it serviced regularly and according to manufacturer's specifications, it would last longer than you and in a heck of a lot more depth than you could stand! But for me, I would not buy an expensive dive watch for myself and even if I received one, I'd be too worried that I'd wreck it. Let me direct you back to Plan A: A Casio G-Shock. :cool2:
Good luck and I hope this helps.
With kind regards,
Thomas