Mark - I may be being a little presumptious but are you looking into this because you are considering doing the St Malo cruise later this month?
The reason I ask is that when Richard took our boat across to Alderney last October he was extremely glad that he had the company of Daniel (another forum member and very experienced RIB owner/driver) so they could share the driving in pretty horrible (and tiring) sea conditions. My personal opinion is that any 'long distance' cruising becomes much safer and more enjoyable if there are a couple of you on board who are able to drive. Plus, a second pair of eyes is always useful for spotting hazards! All IMHO, of course!
P.S. Don't like the idea of being restricted to 3 trips a year though!