I was surprised at the weight of the new controller compared to the stock unit on a Canadian Radrover 5. It's larger, but quite a bit lighter than the stock unit. The stock unit is built like a tank, whereas the new 35A unit is a thin sheet metal enclosure. Longevity is up in the air in my opinion, but I've experienced nothing negative so far for the short time I've had it.
Performance wise, it's working out great. I ride with pedal assist and rarely throttle only. What I wanted was a bit more grunt off the line to get me through intersections quickly and get me up to speed, pedaling on chain gear 6 usually at most. More speed isn't my priority. This new controller provides a much needed torque boost to help out my aging knees. Using the Bolton settings seems just about perfect. His C5=6 setting limits the power slightly, probably to reduce wear on the stock motor. I did change C4 to 3, allowing me to use the throttle while in PAS0.
Wattage wise with the Bolton settings, the max I've seen is around 1200 watts or so off the line on PAS5 while accelerating (or throttle only acceleration), but quickly drops back down when you hit a steady speed. I tend to ride at PAS 1 or 2, and it draws around 60watts and 200watts respectively at speed. If I remember correctly, PAS5 steady speed draw on is around 500-600watts. Range given the way I ride hasn't really changed at all. An excellent upgrade!
I do have some money put aside for the 750watt motor upgrade down the road though. I don't expect the stock motor to give me problems the way I ride at the moment, but I think prolonged heavy use like riding up hills will certainly stress the stock motor to burning out given the wattages this controller can supply.