Dave,
All I can do is tell you that mine has never let me down and only been adjusted once on nearly 5 years. Engine oil into the edge at the top and it's always been fine. I think the lapping makes a huge difference.
The tips I got from e-blag.
I've cut everything upto and including stainless without much issue. I wanted convex and concave turning and that's what these gave me.
I could bore you with hundreds of photo's of things I've made with mine, Here's just the one... All in stainless.
let me know if you want to see any more

Bearings will no doubt work as long as you can set them up properly and you keep them in good order.
The Bedair design I used and adapted is very solid and just simply, works well.
My main adaptations are a double step on the turret into the base (triple if you count the spigot where the bolt threads into) and the single fixing double sided tip.
I've got hundreds of pic's of the mini ball turner build and quite a few of my (made for the job) ball turner. if you want any just ask.
Ralph.