I have an 08 M8 sp, and my wife has an 07 600 RMK w/ the we shocks. My dd went out last season so rode my wife's sled a few times, and the first thing I noticed was how much easier it is to turn/get the m8 on its' side. Poo is easy, just not as easy as the cat.
The only complaint on my 8 is the handwarmers suck...would definately buy another cat. My grand master scheme is to sell the rmk in the spring, keep the 8 for my wife, and buy a new cat!