Extra 12 is similar to M10 in that there is less track in contact with the snow and a higher center of gravity. That said, I've found that limiter strap and front spring/ski pressure is less of an issue than the carbides you run. Having had several of sleds with these suspensions I have found that Woodys Doolys solve a lot of handling issues, especially darting which is what they were designed for in the first place. You might also consider studding the track, not a lot but 96 up the center for a 121 does a lot to settle the back end.