Gotta agree with Wavehumper here - flooding hulls are meant to flood. If you are carrying a lot of divers & kit, you will be more unstable with the hull dry, maybe dangerously so if the weight shifted to one side unexpectedly. You could find your divers being tipped off the side prematurely.
It may take a bit more power and/or time to plane with a flooding hull, but once you are up, its then becomes a dry hull, so I feel that you will simply be sacrificing stability at low speeds and when stationary.
I have said elsewhere that I found my current rib 'skittish' when I changed from a Searider. I think you may find it a bit more than 'skittish' with the holes bunged up.
But then again, it's your boat..........
"Remember the Plug!"