I take it those are custom built boxes Mario, right? They look well suited for my use if they can fit inside a 54mm dia 40mm wide wheel.

Better stick to brushed motors then, rather than getting into problems controlling a brushless setup. That said I think I've seen a local team using a brushless setup on their robot...not sure tho as I only saw a photo of the underside and what looked like two brushless motors. Will try to find the photo and post it here, maybe someone can identify the components.