The Bionx re-gen system seems to only accept so much charge at a time. Going down a steep hill, the regen is not really a serious braking force. Going down a mild hill is where it works best as a brake and battery charger.

Bionx currently (as of September, I think) is recommending REV 59 even though new models had REV 61. They dialed it back for some reason. I had mine reflashed to 59, but didn't notice any difference.

I think the G2 motor (48V) being lighter than the G1 motor has a shorter time before it starts to shut down due to overheating, IF you are doing serious hill climbing. The figure I heard was 4 minutes of hard use for the G2 compared to 7 minutes for the heavier G1 motor. The "mountain mode" was put in to improve things on steep hills, but I can't tell any difference in assist from mode 4 and mountain mode (5). Oh, to get to mountain mode just get to mode 4 and then hold the + button on the console until the screen starts blinking.

Yes, the Bionx system is very well thought out and executed. To me it was well worth the cost.