I chased concentricity hard a few years back until I discovered Lee Collet Neck Sizers. IMO, if a reloader who reloads exclusively for hunting would use the Lee Collet correctly then that would take care of runout enough so that he could forget about it and spend his time on other things. I did try one Redding Type S Bushing Die for a 30-06 but the runout was not good. Perhaps that was not enough of a test. Back then I was not into turning necks.
One thing to remember is that if you remove the expander ball the bushing dies push all the imperfections in neck brass to the inside of the case so they may not be as evident. Then you should ream the neck to get consistant neck thickness. If you leave the expander ball in then you have all the problems associated with those.
I have a Lee Collet Neck Sizer for all the calibers that I reload for except a few. For a 338RUM that I have coming I am going to try the Redding Bushing Dies one more time. The Lee Collet do not create a lot of neck tension but that can be readily fixed with a Lee Factory Crimp Die. Those are easy to use and you can crimp anywhere on the bullet, no matter your seating depth. In side-by-side loaded-at-the-same-time shot-at-the-same-time tests, the Lee Factory Crimps have decreased group size by an average of 1/8" and increased velocity by an average of 10 fps