As an experiment I temporarily replaced (bypassed) my Moscow Plus controller with a FSESC 4.12 50A controller based on the VESC programming format. This is a 60V max controller with tons of programmability. It will even analyze the motor connected to it to optimize controller parameters. This controller is used for everything from RC cars, electric skateboards, and 2500W ebikes. I'm using it in the "sensorless" mode, meaning it's not using the Hall hub sensors (even though the controller is capable of Hall sensing). Anyway, what I've learned is that my top speed can be pushed to about 25 MPH on flat ground with no pedaling. Max speed is ultimately limited by the DC battery voltage provided to the controller, which seems consistent with Leon Cyles claims with their uprated display. My top speed was done at ~53V battery voltage, just about max charge.
My biggest issue is that I have friends with 28 MPH ebikes and I can't keep up on long straights, so I was looking for more speed. I'm looking at ways to boost the FSESC controller voltage to around 60V to get the higher speed.
I also learned that the Reention battery has a self-resetting over current feature that kicks in around 25 amps. I had to reprogram the FSESC to keep under the limit.