Craig, this is the setup I put in my feather for last week's Champs. It's a 2.4kw inrunner, through a standard 16:1 Saturn, running 5s LiPo. The motor peaks at over 30,000rpm on this voltage, so pretty abusive on the gearbox, but no ill effects as far as I can tell after a number of intense fights. I'll strip the gearboxes at some point for a closer look. Of course, two of these were pushing just 13.6kg, shoving 100+kg is a different animal, but it's promising!



And the units in the machine: https://dl.dropboxusercontent.com/u/...3/_MG_9144.JPG (thanks Mark_m)

Another option is to machine down the ring gears, and use only the second (beefier) 4:1 stage as the first stage of a compact HW scale drive system. I think that would be pretty robust.