Looking at it a little more carefully, the primary purpose of the RoboClaw’s position control is to reach a specific position and stop, which sounds like it might not be very useful for your application.
Our #2267 NEMA 17 and #1474 NEMA 23 stepper motors might work at 900 RPM if you use a high enough voltage supply. The pull-out torque curve in the datasheet for the #2267 NEMA 17 motor shows about 20 N*cm of torque from the motor at 5000 half-steps per second (using a 24V supply), which is about 750 RPM and higher voltage supplies allow faster speeds with stepper motors. This thread here on our forum might be useful for more information about getting stepper motors to work at high speeds.
Stepper motors tend to hum at the frequency of the step rate so using finer microstepping to smooth the motion and increase the step rate above audible frequencies might help. Also, using a lower current limit (which will decrease low speed torque, but should not interfere with higher speed operation) will also decrease the volume of the humming.
Our TB67S249FTG Stepper Motor Driver Carrier works well with low resistance and low inductance stepper motors like the two I mentioned.
-Nathan