I have spent quite a bit of time on a RT1000 with a Dynoport single exhaust setup, basically stock other than that. It was a 162" track, which I think is too much.
Will it be competitive with the M1000, for sure, they each have their strong points. The RT has crazy bottom end (TRA clutch) and phenomenal traction with the 162" on hardpack or in the deep. Sometimes it seems like too much track ever for that powerful machine. It could use a box to tune out a rich spot around 5800rpm with the pipe, but other than that the machine runs spot on. It's heavy, don't deny it. It feels about 50lbs heavier than the M1000, and the skis and front suspension need work to get ride of a nasty death wabble it will get you in on the hardpack off the throttle in some bumps. New skis and more preload would help there. It's super plush on the bumps up the trail too. Great machine, just too big and long (in 162", 151" may help that part), and definitely tires you out even quicker than the M1000 will for it's size in weight. I got on an XP and thought it was such a nice break after wrestling the big 1000's in the deep for a few hours.
The M1000's will lay over almost upside down in a powder turn if you want with little effort, the Rev's/XP's you have to kick them over hard on one running board to motivate them to get completely sideways like an M-Series does. I can go downhill on my M1000 sitting and just turn the skis and lean it right over completely on it's side for however long I wish and flip it over to the other side in an instant. It takes alot of effort to get that RT to go some places, and I'll tell you what, if she don't want to go there, you won't make it go there! When that big sled starts to go one way or another, if your not on top of it before it moves it will pull you down with it. I'm 195lbs without gear and can throw my M1000 around like nothing, and can make the RT move pretty good, but nothing like my M. Just the way of the chassis. I can see it getting better with the 151" track, but not by much enough to make it feel like it lost 50lbs.
The Powerclaw on the M1000 and the tunnel changes could only make it better for the big M10. Price you pay for power/torque of the big boys I guess..... Both are great sleds, no sled today is a "BAD" purchase. Just depends what you want a sled to do for YOUR type of riding. I definitely would only recommend an RT1000 to 200lb+ riders, it has alot of room for anyone over 6' tall.