Re: Full length or neck. Do you see a difference?
From what I've seen, the benefits of neck sizing depend largely on the gun. One thing that may make neck-sizing only sub-optimal is that w/ some factory guns, the sad reality is that the chamber is not cut 100% concentric w/ the bore, and if you neck size only, you may preseve the skewed dimensions of the case, only to have the case not indexed the same the next time it enters the chamber, and therefore but weird and possible detrimental stresses on the case. In these situations, full-length sizing may be less problematic, as the case will sit the same in the chamber every time.
One benefit of neck sizing is that you can control the neck tension (assuming neck diest w/ bushings) on the bullet, which can help sometimes, in having the case neck release the bullet easier upon firing.
In any event, try it on your gun, and see if it works for you.