Apart from the 6 wheel layout and length of the chair, I think this one does show some potential speed/power-wise.
Looks like a lightweight guy driving it but in the video, it does handle the snow pretty well.
http://www.turbo-twist.ch/en/index.html
Came across it through an article on wheelchair soccer demonstrations during the breaks of the national cyclo-cross championships.
They're demo-ing the Turbo Twist Sport there as being 'the Rolls-Royse of wheelchairs: small, very agile and fast wheelchair'
http://www.turbo-twist.ch/en/sport.html in wheelchair-soccer setup.
http://www.turbo-twist.ch/en/turbo_twist.html civilized version is a 5-wheel setup. One rear central wheel.
Available with R-net 120A controller.
I wish I had my BM-clone finished to take it there for a comparison and maybe a challenge