Ok, good title, but I'm not sure where to go with it.
Technically it's probably true that more float = harder to get out of holes because the best way out is usually to sink to the bottom of the hole to hit the flushing green water. Practically speaking, the difference is probably minimal because you'll be able to swim to the green water if the hole doesn't do it for you first. Holes flush entire boats underwater, so I don't think it cares about an extra few pounds of flotation on your vest. If you're stuck in the aerated water, extra flotation won't make as much difference anyway.
And of course another important consideration is you want a vest to keep you high floating through a rapid so you can get air and swim to shore. In that case, the extra flotation can make a huge difference.