Hi, as usual this is a request on what I have aquired, not application based. I basically have some old RH5, RH8 and RH11 harmonic drive DC brushed servo motors fitted with 1000 line encoders. These range from 12v to 24v with peak current draw from 0.8 A to just over 2A and gear ratios from 50 to 100:1. My main use tends to be positional (telescope drives, focusers, 3D printing). The problem I am communing up with is that there are plenty of large drives eg Gecko G320x that I am familiar with from my CNC days but not much that focuses specifically on low amps with incremental encoder feed back. Just asking if there are any suggestions on the Pololu front (JRK?) or other users experiances that would help. At the moment the drive is looking 3 to 5 times the physical size of the motor 
Hello.
I am not very familiar with the Harmonic drive servo motors, but I noticed you mentioned brushless in your title and brushed in your post. If they are brushed DC motors, and you want something that supports using quadrature encoder feedback for position-control, you might consider the RoboClaw Motor Controllers. The Jrk G2 Controllers you mentioned might also be an option if you want to do closed-loop speed control using tachometer feedback (they require analog feedback for position control).
Brandon