NFLD-Nytro
Your plan sounds like mine. I kept my xtx which is now virtually stock (except for skis) and bought a leftover 2011 MTX 153 this fall which I modified the hell out of. I wanted the paddle track for those epic powder days, but kept the xtx for tourning/trail duty and pack sack runs lasting a few days. Reliable, comfortable, and pretty good all around performer...no plans to part with the xtx.
Then there is the powder question.....and I agree with Sonds.... you really can't get one sled that does double duty....WELL.
From what I gather (and I got to get to the rock soon to see for myself), Western NFLD is even more suited to a powder sled than Northern NB, so a mountian machine simply makes sense. I'd say I am 60 - 70 percent boondocking powder so my first interest is a mountian sled.
Which one? Well thats a personal choice. I stuck with the MTX, because I simply love the engine and at sea level, a 140hp is enough for me. But after you replace front/rear suspension and do bunch of other "stuff" to make it a real(er?) mountian sled, not sure I would do this again...its a pile of work and $'s. I love the new 2013 RMK and the 2nd year AC 1100T will also be a good sled once the kinks are worked out.
All that said, I just finished putting the first 150 km's on my 11 MTX this week to get it past the 6000 rpm "break in" and I must confess, with the skinz front end and power claw track/AC rear suspension, and having shed maybe 50lbs, this thing is an absolute riot to drive.
I'm not a huge climber...more of a slalom rider/trees/technical and IMHO I find the nytro weight a bit of an advantage, in that it's weight tends to slow down its reaction and therefore tends to be more predictable rolling off and onto the side. I've never driven the Poo, so I can't comment, but I have driven the AC Proclimb M800 and I found it bit more of an all or nothing sled when committing to your turns.
I think in the end (this time), reliablity, torque, balance, fun factor and dealer tipped the scales in favor of the MTX. In 2 years time...it'll be different again!
Good Luck
OTM