M-10 is a great suspension. I works mush better as a "cruiser" suspension as opposed to a "ditch banger". The M-10 "feels" and reacct differently than the OEM suspension, its hard to describe. It absolutely eats stutter bumps up, its on of thestrong points of the suspension. The problem with the M-10 is that it needs constant adjustment to get the most out of it. I would say that if you are considering getting an M-10, try to find someone who has one that you can try, to see if its for you or not. I personally think that the stock Firecat suspension is a better all around suspension.
BTW: FAST does make a 128" M-10 for the Firecat.