Larry,
If one looks at the amount of "work" that is being done by the expander ball on a typical one piece die, he will surely see that the die manufacturer has erred on the side of safety to a degree that even taking into account the variance in neck wall thickness from brand to brand, and lot to lot, the ID in the neck portion of the die is smaller than it has to be. Also, if one reduces the amount of expansion that is required, and uses a good dry lube inside of the necks, the amount of expander pull during sizing can be significantly reduced, to the point that the "evil" expander ball does not cause necks to be cocked during sizing.
If one is shooting a factory chamber, with generous clearance on the necks of loaded rounds, one can run into problems with capturing the end of the neck in a bushing's lead in chamfer. There are also some issues with bushing float that can have negative effects, as well as bushing concentricity and squareness that can also come into play in tight neck situations. Bushing dies are almost always better than a typical one piece die, but may not be as good as an optimized one piece, even for unturned necks.
Some time ago, I was discussing the relative merits of Lee Collet dies a compared with bushing neck dies, with a bullet mfg. technical rep. He did a side by side comparison with unturned fired brass from a factory chamber, and the collet die won. That is why I suggested the body die and collet die approach in an earlier post. My later post draws on my experience with my Savage .220 Swift. I have a CH/4D FL die for it that has a custom neck ID. It works much better than the stock die that I was previously using, and produces admirably straight cases, when used with care. One of the first things that I would encourage a factory rifle shooter to do is to pick a brand of cases, and stick with it. This allows one to pick a bushing or custom sizer neck ID that is a better fit.
We in Benchrest generally turn necks and have minimal neck expansion. What works best can be a little different for unturned necks and factory chambers. By letting an expander do just a little work, but not too much, the uniformity of untruned neck IDs can actually be enhanced without cocking necks during sizing.