We're using a 7'6" zodiac with a slatted rollup floor. Serves the purpose though our 10 foot kayaks are our primary shore transport. Nice to be able to roll it up and bag it below when it's not towing conditions - keeps the decks clear.
You're not likely to plane very well with a small o/b anyway so the lighter less stable bottom isn't much of an issue to us.
1984 Fast/Nicholson 345 "FastForward"
".. there is much you could do at sea with common sense.. and very little you could do without it.."
Capt G E Ericson (from "The Cruel Sea" by Nicholas Monsarrat)