Looking at revolutionwork, the system looks a bit more bulky than qiroll. I expect it to be heavier although I don't know by how much...
Also, it looks like I wouldn't be able to use my own batteries from their FAQs...
"Can I use other battery packs with Revos other than the one's that you supply?
Sorry no. The batteries are matched to the motor controller and the Revos won’t work with another battery and may even be damaged by it. Our batteries are excellent value for money and you can obtain another battery from us on its own if you want to"
I still sent them a message... will see what they say