I remember seeing someone use them on a partially built heavyweight back in, I think, 2006. The robot never got finished and I don't think the guy ever made it to events, it was just a build thread on the old Technobots forum as they used to sell those motors. It did get to a driving stage but I can't remember how well it performed.

Not a particularly helpful post and I'll leave it to others with a better idea as to their suitability, but for something that seems to have similar specs to a Bosch 750 but for much cheaper, there must be a reason for their lack of widespread use in heavyweights other than people not having discovered them yet.