L'Enfant Perdu is a stunner no doubt about that but I'd not take to her as a long term cruiser. Would make for a fine racer and be pretty cool for weekend cruising but nah, not for long term.
btw .. am I the only one who has concerns about those vertical blade keels ? I'd hate to think what would be left if you hit a whale or even a sunfish with one of those things.
I don't think that should be a problem bigger than in most fast boats. At least in that one you would have two rudders that are the more fragile part of any boat. You could lose one and you would still have steerage, limited, but enough to sail slowly and get away with it.
However those that like narrow hulls (me included) should be aware that means necessarily a lot of heel and that if the boat is sailed fast that does not really means a comfortable motion:
YouTube - route du rhum 1
The heeling reason has to do with the way the boat gets its initial righting moment, the one used to carry sails:
On a narrow boat there will be little form stability so that power come from the ballast. That's also why narrow boats need more ballast to sail. The ballast does generate very little RM with small angles of heel. You need to have a lot of heel for the ballast to be really effective.
On a beamy boat most of the RM comes from form stability and that is generated with small angles of heel. That's why beamy boats needs less ballast for sailing and sail with a lot less heel. Of course, in what regards reserve stability and inverted stability all the advantages go to narrow boats.
That's why I prefer a mixed solution, a boat not too beamy but also not to narrow. I would say that for a 40ft that means a beam between 3.70 and 3.90m. L'enfant perdu (40ft) has 3.16m