I have LOTS of experience on stiletto 27's. And I live in RI and am very familiar with the conditions of teh North Atlantic. I would say three things
1) Get a 27 with daggerboards not a centerboard
2) If at all possible get a 27 GT, it is two feet wider than thestock 27
3) A 27 is more than enough boat. I have been on these boats in 25 kts plus many times. The only time I have ever heard of someone flipping one is while racing in over 20kts with the kite up pushing it as hard as they could. They are really great boats in a ton of breeze. They have lots of volume fwd and aft. In my view they are an extremely seaworthy multi. I would not hesitate to sail one from Newport to Long Island in any but the most extreme conditions.

charlie