Man oh man oh man... There is some significant BS, off topic rambling, and complete FUD in this thread.
First of all going off trail (Boondocking) isn't any more dangerous than on trail activities, **** I'd say that off trail is on par with ditch banging in most circumstances.
A ditch has cement culverts, fire hydrants, and other misc dangers that you can't see under the snow, yet I don't see any of you arguing against ditch banging in here.
Finally to get back on topic, which the OP was asking about was the difference between a mountain sled and a crossover sled, simple as that. While I can't comment on the direct question(s) myself, I can say that crossover sleds are definitely NOT marketing hype and BS. Going from a 2002 XC SP 600 trail monger to a 2010 Switchback 600 w/ 136" track I can definitely tell you there is a huge difference. While I can't say if its the chassis difference or not (Edge vs. IQ) the ride is substantially improved, and the longer track allows me to go ditch banging in some of the deepest snows I've seen in 20+ years and not have to worry one bit about getting stuck as easily as I did with the 121" track on my old sled.
And again to the OP, just remember the saying, "Opinions, everyone has one" (kept it clean for the forum but you know the gist)
-Josh