Regen won't work with a mid-drive or a geared hub motor. OP, get disc brakes. If Avid BB7s are a great option: not to expensive (compared to hydraulic), easy to adjust, and the most ebrake cut-off levers will work. FWIW, I ride with only BB7s on the front and regen. Plenty of braking force. That said, I work for an ebike company and I would never recommend to a customer that they cruise with only one brake.