My husband and I have had the earlier generation 305 around 4 years now and no problems.Would definitely get the upgraded water proof one once these blow up.
I have a few friends with the Garmin 410 and at least 1/2 of them experience ongoing problems from needing to load patches to the watch not working during a race.Supposedly these problems arise due to Garmin's switch from analog to digital (or the other way around) and that is why they went back to the 310XT (newer version of 305) with added bonus of being able to wear in the water.That doesn't solve your watch dilemma I'm afraid.Good luck with the purchase!
My 310XT was delivered yesterday so I have been having fun playing with it. You can access the "watch" under time of day and set it as one of the views as a full screen. This works perfectly for what I need and very happy so far that this is the route that I went.