125 & 250:
Other than the engines 125 (15-HP) and 250 (22.5-HP) they are physically the same bike. Virtually identical weight (about 200-kg), [2]12/12 wheels, and wheelbase of 1490-mm.

400 & 500:
The MP3-400 (34-HP) and Fuoco-500 (40-HP) also appear to physically be the same bike with different cosmetics only. Virtually identical weight (about 240-kg), [2]12/14 wheels, and wheelbase of 1550-mm. Just to be clear, the MP3-400 is not the 250 with a bigger engine; the 400/500 has a longer frame and a larger wheel on the back. I read a review of the Fuoco where the rider asserted that it was geared lower than the Beverly-500 to allow for a more rapid acceleration from a stop despite the additional weight but that top end was subsequently reduced. There is an unconfirmed rumor that while Europe gets 125 & 250, 400 & Fuoco-500 the USA might get the MP3 with the 500 engine rather than the 400 engine (and of course, the 250 but not the 125). Swaping the 400 for the 500 engine would be easy as they are the same engine with the 400 simply having a smaller bore/stroke. Either way, 400 or 500 it's likely the seat-of-the-pants difference between 34-HP and 40-HP will minimal.

Gilera MP-800 & Aprilia MP-850:
Just dreaming. The Gilera GP800 scooter and Aprilia 850 Mana motorcycle both use the 840cc V-Twin engine mated to a CVT - they could certainly build a 3-wheeler with that engine. The question is whether the dual front suspension of the MP3 would be stable at 100-mph+ speeds. If it were possible, a MP-800 scooter or Aprilia MP-850 3-wheel sportbike would be very interesting indeed.

Trivio 3-Wheel Prototype: