In 15 years and many dozens of .204" arrows tested or used, I've never seen the concentricity issue. I would imagine that showing up on an arrow spinner as wobble. But gee, isn't every insert that's put in an arrow smaller than the ID of the shaft? So wouldn't that be a problem for all inserts if that really was a problem? On my RIP TKO's the brass HIT's wouldn't go in at all. I had to screw them onto a concentric field point that I tightened in my drill, and then held some 600 grit Silicone Carbide paper against them while they spun. Worked perfectly, and probably created an even better bond with the arrow shafts.
The mushrooming thing I only saw on certain arrow types, but not all. So as I've always said......if folks are going to use arrows that mushroom, then use the collars. But IMO the only way they can mushroom is if the epoxy bond is broken. And if that's the case, then even a half out can push back into the arrow if the bond is broken.