I too have been looking to expand the capabilities of my buffer that I built:
http://straightrazorpalace.com/works...-part-one.html
However I'm very concerned with the tolerances of the products that I've found online. The same machinist (referred to in the original thread as Pee Wee Herman) is also concerned. He tells me that the higher the RPM the more any imbalances (wobble) can work on the bearings. He's doing some research for me and had asked me for measurements of my (1/2") shaft. I found it to be between .497-.499 probably due to me polishing the original precision tolerance shaft that he'd had me purchase.
I doubt that you would have a dial readout setup (I don't) to check for run-out but I would think that once you have them in place listen to the machine and watch it carefully. I would think that once you shut the buffer off watching it would be of some help.
A good reference point would be to have run it before hand.
I hope this has been of some help.