If it's the same bike as in this review, Court says 48V is an option, so it's probably the same 500W motor, and if you're lucky, the controller will adapt to either voltage when the battery is connected. Call Motiv and ask them. If you ride conservative, the motor should last. Looks like a pretty big motor.

I would expect that a Motiv controller upgrade, if required, could be an expensive part, but still might be better than a third party controller. One of those with LCD display plus all the extras like brake levers, throttle, and pedal/speed sensors will be $70-100 from China and require e-bike building expertise to connect, plus it won't integrate with your bike as well.

A 48V 11 AH battery gives you about 100 more useable watt hours (132 in theory), which is probably 10 miles. Maybe 22-24 mph too.