Not much between them Andy. The controller on the Ezee is a 20A, I think the Big Bear is too. The BB is a 26" wheel whereas my conversion is a 700c. What this means is that the Ezee outspeeds the BB on the flat (setting for setting), however on the hills the BB will slowly outstrip the Ezee. My theory is that the smaller wheel size allows it to develop more torque.
However they both have some serious, grin causing pull and, having recently done a conversion with a Panda kit, realise just how much. Nothing wrong with the Panda, but it's a bit like putting a Suzuki Jimmny up against a V8 Landrover.
Oh boy, now I'm for it !