That's pretty much my opinion as well. Especially if you do a lot of sitting in a drift boat or raft. The endless bunching of that area I think wears the zipper out faster.
If you just walk and wade, or stand in a sled, theres less chance of them wearing out, but it's still a weak point, bound to fail at the worst possible moment.
I have the G4 Pros, have had them for 4 years now, have had zero issues. I doubt I'll ever get a zippered pair.