I bought a used HPV Gekko a few years back and since I'm getting along in years and have a few physical problems I decided to put a motor on it. I did some research, reached out to someone that seemingly knew what they were talking about and wound up with a Tongsheng kit, that 'included' a throttle. I installed the mechanical part of the kit but when I was wiring it, I found that even though it came with a throttle there was no way to connect it to this particular motor.
I tried it for awhile but the amount of force needed to pull away from stops or top hills was too much for me. I also did not like the 4 step torque sensing PAS system.
This year I bit the bullet and removed the Tongsheng and installed a Bafang BBS02 kit. It works much better for me, I have a throttle if I need it and I like the 9 step PAS. It's actually fun to ride where the Tongsheng wasn't. That's from my 80yo perspective.