While the possible weakness in the 56mm gearboxes leaves me with some concern, the "don't stall the little gearboxes" warning was made last year.
http://www.chiefdelphi.com/forums/sh...light=banebots
In the right application, with proper design the small BB transmissions work great. We used a 5:1 reduction running off an FP on our shooter last year with no problems... and have a couple 256:1 ones sitting on the shelf waiting for a job to come along for them. Since they will run off FP's, which let out the "magic smoke" pretty quickly as they approach stall, we try to keep the FP's down to 10A or less and within the torque limits.
I am sure that as I type, however, there are people working on clarifying any problems with the 56mm gear box and developing a solution.
I'll keep my fingers crossed,
Jason