CBP sells the gammet, trinkets to submarines. They do not make anything. The different ATVs are made at different factories, just like tractors. Any issue with missing or damaged parts, is going to be more an issue with the particular factory/ATV than the broker.
I have no direct experience with the ATVs, but would assume some issues, unless you get direct feedback from someone that has had a load or two delivered. So, make sure you ask the questions, and have a resonable idea of what getting parts out of china will take. Cycle times could be more or less than a tractor part. Also, should be somewhat cheaper and easier due to smaller weight and size. While I have seen a couple of sellers on the net, I suspect retail parts stateside are harder to come by than Jinma parts.
If you are looking for a less risky purchase, talk to Puma Machinery or Tractor Outlet. I think they are selling ATVs via crate, but should have stateside tech support and parts. There might not be links on their websites, so might have to call or email.