From what I've messed around with I can't see a hover / fan powered robot ever being that competitive.

And if the entanglement rules got relaxed people would soon start panicking about their drive belts getting damaged. EO's want maximum damage for entertainment value, and have crippled other builders by making the means to defend themselves illegal. So now most weight classes will become spinners and bricks. Relax the rules and we'd soon have a plethora of weird contraptions designed to bind up spinner blades.