Hey Wishbone,
Thanks for the post and your experience on black carpet. I could imagine the aluminum chassis would feel very well on black carpet. I ran my carbon chassis without any stiffeners and I just could not get the edge of traction rolling out of the car. Now that I put the X-brace- on behind the motor, the car feels much better even on asphalt. Perhaps you have read my post above but I am replacing the top that will be slightly stiffer . Perhaps with it I will try the carbon again on black carpet.
As for the front belt coming off. I had the same issue. A friend of mine that runs a mid motor car (Gizmo) told me mid motors run the front belt slightly tighter or run a front belt tentioner. I made it one notch tighter and I have not had any issues.