Did you end up buying it?  If so, was it reliable?

I?m super-glad this forum exists!  I too recently bought a Radcity 5 Plus and although it initially worked, it would randomly stop working.

We have a Rad Bike retail outlet about 40 minutes away, so after a dozen unsuccessful attempts to connect with their central support staff, I loaded up the bike and drove it to where I bought it a week ago.  I was there for about an hour and in that time had 1-1 conversations with two different service guys.  What I learned is that [1] this is a known issue with a specific component set; [2] it?s an EMI (electro-magnetic interference) problem between the brake sensor and the throttle on the right side; [3] the throttle should work if you disconnect the right brake cable.  The problem with #3 here is that the right brake is the back brake and you can send yourself over the handlebars if you lock up the front brake with the left one.  The good news, though, is that if this is the issue, you could limp yourself home.

On another thread from a couple of years ago here I saw that someone was saying that if you ?pump? the right brake (or the left brake, according to their post) once or twice, releasing it quickly rather than gradually, that resolved the issue.  I haven?t had the opportunity to try it yet, but Speaking as an engineer that knows a bit about EMI, that makes sense to me!