Trimix - I've not been to Corsica, but all of the med can get a bit of chop on in a breeze so I wouldn't assume you don't want a good hull.
More V cuts through waves better but requires more power to drive it. Less V = smaller engine so cheaper package/higher speed but less comfort. The difference is noticeable even in small waves and sensible speeds. Whether it matters to you is a different question.
Chines, spray rails etc are a bit more complex. Are you looking for speed, comfort, minimum power, tight cornering etc?
If you are going to spend a lot of money on a rib - you might want to look at something like this: BOOK REVIEW: The Complete RIB Manual, Dag Pike