The v1 Revos I have is unsensored so a little noisy at times but once going it is mainly tyre noise, the v3 current model is signwave/sensored so should be much quieter though I haven't heard one in use. Panny Pf cells were used but they could do better and use 3500mah cells for 20% more range.
How reliable the drive for long term use we don't know.
The company are in Brizzol so if localish one could contact them to see if a ride on the test bike is possible.
Not the cheapest of kits but it is lightweight, needing no real knowhow to fit.
One would need to find a way of securing a rear mudguard as it will need cutting to allow the tyre contact for the drive unit. It is a minimal, no fuss kit with nothing to clutter the bars .