I've been using an electric unicycle for about ~1year now.
It took me about 8-10 hours of regularly falling , or stepping off to get the basics down .. kind of like walking you fall allot at first , or learning to ski , etc.
---
When I contacted RI DMV they told me :
(your state may vary)
When clearly bicycle.
When the non-human power (combustion or electric) provides under 1.5hp and not above 20MPH .. it's the same as a bicycle .. Can use on bike paths , bike lanes , etc .. no registration required , no license required.
When Grey area could be a scooter.
When non-human power is over 1.5HP but under 4.9 HP .. or .. that non-human power goes over 20MPH but under 30MPH .. then it could be considered/classified as a scooter .. if a scooter .. no license required .. registration would be required .. and could not use bicyle path or bike lanes .. however code does not yet include unicycles specifically .. so it can not be registered at this time .. and weather such would or would not be a scooter is still undermined.
Clear when could be a motorcycle.
when non-human power is over 4.9HP .. and/or .. non-human power over 30MPH .. then it would be considered a motorcycle .. license required .. registration required.
---
I don't know what police officer would choose to enforce that .. but .. they could ticket for anything I guess .. and then if you challenge the ticket .. then the court can rule one way or the other .. sometimes a ticket get's tossed by the court , sometimes they don't.
---
The model I got is a Solo Wheel Glide 3 .. I'm told it's hardware is the same as the Inmotion V8 (just a few software tweaks).
OEM:
This model is a ~800watt motor .. soo .. under the 1.5HP limit.
This model is limited to 18~19MPH .. soo .. under the 20MPH limit.
This one gives me 15-20 mile range per charge .. YMMV.
soo in RI .. OEM .. this one is treated as a bicycle , for where I can go , and not needing registration or a license .. even if I'm stopped , I should still be fine.
I also personally like the near bicycle power/speed .. if I want to go 40+ mph I will just get in my car.
When cargo is no more than 1 back pack worth .. it's a good fit.
Over the year I've had mine .. as I build up more condition / endurance .. I see that I might eventually like to have more range .. 15-20 miles is enough for short trips to grocery store and such .. very long range of the higher end models ~80 miles or so really starts to show the massive energy density advantage human fat has over modern Li batteries , as the weight of those wheels goes up considerably.
This model is not one of the ones with built in suspension .. some people have done that after market .. and some of the latest models have that option OEM .. so , my slightly bent legs and the give of the tire are all I have .. so mine is best for fairly good surfaces .. the worse the surface or faster the speed the more valuable suspension will be.
----
I have had ebike's for years .. so why go to a EUC ?
It provides roughly the same (as bicycle / ebike) extremely high energy efficiency .. YMMV .. I see 30-40 Miles per kwh .. in some cases it will be more energy efficient per mile than walking.
It is much smaller volume to transport and store (even than my previous folding ebike) .. this makes it easier to transport in my small car to a bike trail , or take on vacation .. or .. to put in car , and use as my ride home , when my car needs to be dropped off at mechanic .. or .. space store at home when not in use .. etc.
As it is smaller than some rolling pieces of luggage .. I have had no problems walking it in with me on small shopping trips (groceries and such limited to back pack and carried in hands) .. where my ebike would have to be left locked up outside.
Used in the self powered rolling luggage mode .. it still has it's carrying capacity .. on mine that's only ~250lbs .. but there are other models up in the 300-350 lbs capacity range .. in this mode it can act as an electric mule .. and can carry that ~250Lbs for me .. which can sometimes be nice .. and some some of those small trips with back pack full I've been over the ~250lbs .. so a higher carrying capacity might also be something I see as being nice eventually.
----
For amount of physical effort / exercise :
Casual walking:
Standing EUC is more effort / exercise.
Sitting EUC nearly the same .. but using different muscles.
Jogging / running:
EUC stand or sit is less effort / exercise.
Bicycling Down hill:
EUC stand or sit is more effort / exercise.
Bicycle Flat level cruising:
Standing .. EUC is a little less overall .. but a different muscle group .. bicycling mechanically applies the human effort better .. large muscle groups / leverage / etc .. standing on EUC is feel it in those smaller areas like feet and such.
Sitting .. EUC is much less effort / exercise.
Bicycle up-hill and/or higher racing speeds.
EUC stand or sit .. less effort / exercise.