SBarry, the kits are just as legit as bluetooth speaker you mount on the handlebars. Sometimes the speaker falls off. Othertimes it can't find your source. Batteries run down. When working right, it's great.
If you want the convenience of an all-in-one package that can be easily removed, it will cost more and have more tradeoffs. Battery in the wheel does add weight and makes for a large goofy looking wheel. Electronics in the wheel is exposed to more heat. I prefer just the motor in the wheel. Put the battery and electronics somewhere else. Then you can replace those as separate items without being captive to the original seller, who may disappear.