I have both actually. As said above, you need to get the updated parts for the Mototrax. The RAD dampener and the IDS really help. Set up also makes a huge difference in the handling/steering -- the height of the shock under the seat changes a lot, and the 1" base adapter for the ski really helps with ski pressure.
Message me for more details if you get the Mototrax.
As said, the Timbersled is reliable and simpler on the set up end. Just bolt on and go.