I was pondering on the cut out issues at speed for EUC's, and i was wondering that the main issue is down to a sudden voltage drop from the power supply. now, what if EUC's had a small array of super-capacitors that could provide a Life-Saver 1 shot boost to the voltage + current to force the rider back hard and warn the rider that their extra life is now depleted. When the rider is forced back, the motor starts to act as a generator so that should help the system stay stable until a sensible speed is reached.

You do not need an array of supercapacitors to fulfill the entire workload of the battery, just a boost to make up the voltage difference (Maybe 24V and 3A for 1 second on the larger systems (no i have not checked if these figures are correct, I am just mussing this idea)). If i understand correctly, 1F of capacitance = 1A per second, so it sounds like you need a lot of capacitors to pull this off... but then we realise that we still have the battery providing current which offsets the requirement.

I was also thinking that the capacitors would only be charged via the mains to prevent aditional strain on an already weak battery.

This is just my mussings and it may be the case that it is impracticle for many reasons that i do not understand from an electronics / cost point of view... but if someone out there has some Electrical knowledge far superiour to my 20 year old Secondary School curcuit training - then i will be interested in what they think...