I don't believe hybrids leak any more or less then other trailer types, any opening is susceptible, be it a bunk with tenting, a slide, or an entry door. I do believe the best way to minimize leaks would be covered storage. If you are looking for a trailer with the least chance of leaking you might look at 2 piece fiberglass.
I'm just finishing a floor replacement on my hybrid, the damage was in the area of the sink, entry door, and the 2 pass thru storage doors. There is also some just starting where the water heater goes through the side wall. The floor at the bottom of the walls where the bunks are is fine, as is the bath.
I would agree with you, if there is a new floor it is likely it had soft spots, also in all likely hood it was not fixed correctly. Few would be willing to do all the work required.