The Garmin GPSMAP 76CSx or 60CSx are both well liked.
One issue is that Garmin's waterproof rating doesn't seem to always be right - after going through one (and hearing from others who also had units ruined by water ingress), I now only use my inside a clear Aquapac dry bag.
I just got a Garmin 310XT. It is a GPS watch that tracks where you have been and then automatically uploads it to your computer. Having it has pushed me to go faster and get better workouts than before. Its also nice to see where you have been. It is rated to 50m, so it is very waterproof. However, if you are looking at the Garmin 72H, then I suspect you are wanting maps to navigate by as you are kayaking. The Garmin 310xt does not do that. Before this I was using my iPhone in a waterproof case and an app called Motion X. That worked fine, but if I went for a long 3+ hour paddle, the iPhone would loose power. Here is a good site with reviews and links to reviews: http://gpstracklog.com/2010/06/garmin-gpsmap-78s-review.html#commen... They suggest that the Garmin 78s is one of the best Garmin units for marine use... Hope this helps, sorry I don't have personal experience with the 72H.