We raced GtoP several years ago. Typical light sea breeze conditions with 5-7 knots at start, built to 10-12 later in the day, and eased back to 8-10 for remainder of the race. We sailed upwind, close reached, beam reached, and sailed downwind. We had a match race going for nearly all of the race with Zydeco. Even though we were scored in different divisions, we finished about 10 minutes ahead and they corrected out by 12 seconds over us (24' Corsair trimaran versus J-111). For a result that close in those conditions for a race that long, I would have to believe Zydeco enjoyed the race as much as we did.
A non-foiling offshore capable trimaran IMO could be rated fairly with a multi-rating system (like ORR) to race against higher performance monohulls especially boats like the M32's, J-111's, etc.