My Ulton GTR has just arrived so I need more time to play with it but I can say that the machining is excellent on it.
Threads are perfect and chimney screws on deck easily without catching or cross threading. It all looks quality TBH.
Interesting what you say about the ball bearing. I don't know if it'll get rusty but I'll be keeping an eye it now and will let you know. Also, I notice that the original manufacturer is selling the ball bearing and spring-loaded housing as a purchasable part so maybe FT etc... will do too in the near future. Looking at mine, it looks like the ball bearing housing can pop out for service/cleaning - you have to take the positive pole out first which exposes a hole which you'll use to push the ball bearing housing out. I haven't tried it yet though...