Well, I'm completely inexperienced, as the only dives I've done are my pool and cert dives, but I've used contacts for all of them. I have extremely sensitive eyes and virtually NEVER wear contacts, but even so, I had no difficulty with them on the dives. That includes during the cert dive when you have to do the no-mask swim and sit there for a minute without your mask. After I put my mask back on and cleared it, they were a little bit blurred, but corrected themselves pretty quickly after a few blinks. I'm not sure if others have had problems, but I will continue to dive with contacts until I manage to get lasik. I'd say go for it, personally.
One thing, though...I wouldn't recommend opening your eyes underwater without your mask on--if it gets knocked off, keep them closed
