I've ran and won with the MINecon in super heavy 425. There is no weight restriction for the MINecon. However, it will be at a disadvantage at higher biting tracks and will be tighter at heavier weights (in high bite situations).
The best of both worlds is our new Scythe chassis, as it uses 1-1/4" frame rails but flexes just as much as the MINecon. So, you will have both BITE and ROLL SPEED!