The only thing that I can think of that has not been said (the wrenches REALLY need improvement though - the two that came with my starter kit are completely rounded off (my replacement wrenches have ball-point ends... awesome to work with and they haven't rounded yet:
this or
this style)) is rubber coated treads. While the treads do well on carpet, the performance on hard surfaces like cardboard is really sub-par. If there was some sort of rubber coating it would be perfect; I have put rubber bands around my treads to get the same sort of effect.
Keep up the great work Intellitek!