We preferred the inflatable floor,we found it keeps the dinghy more rigid and if any water does get in it tends to stay under it so we do not get wet.
Disadvantages is that it is something else that can get pierced. But when we had to change the last dinghy the floor was fine, the dinghy on the other hand had more leaks that George Osbourne's budget
We much prefer the inflatable floor, particularly in combination with the inflatable keel. More directional stability when rowing and motoring. The only disadvantage I know of is that small shingle gets between the floor and the bottom and makes a sharp lump, which would presumably puncture easily.