I don't neck size and I won't. Neck sizing is primarily for lazy people. I don't believe that it improves accuracy and I have seen that it is detrimental for function.
I still shoot every weekend that a match and the weather cooperates. I don't know anyone, XTC shooter or Long Range shooter who neck sizes. You neck size and one day the case will stick in the chamber. To get the thing out you have to break position, find a cleaning rod, knock the thing out, and all the while the clock is ticking and conditions are a changing. To spend all the time, money and effort to get to a match, only to blow your score with crappy ammunition is stupid.
I do not recommend hunting with neck sized ammunition, especially against something big enough to eat you. Even if there was the slightest accuracy advantage, I will take function reliability ever time. I want my rifle to feed and extract. Other people may disagree.
As for brass life, I fully length resize, using small base dies in every caliber I can find them. I bump my shoulders back about 0.003" and case life is exceptional. Belted magnums are a poor design and since the base to shoulder distance is not standardized, unless you buy one of the special gages mentioned in this excellent article,
Extending Cartridge Case Life http://www.realguns.com/Commentary/comar46.htm case life of a belted magnum will be short.
First time firing a belted magnum, I lube the heck out of the case before shooting. Lubrication on the case breaks the friction between case and chamber and that prevents sidewall stretch. Given that the shoulder to base distance of a new belted magnum case has nothing to do with base to shoulder distance of any rifle, because only the base to belt distance is controlled, lubing the case first time prevents case head separations. After that, I use the special case gage and bump the shoulder back 0.003".
Lubed cases shoot fine. I slathered these cases with Hornady lube or paste wax before firing, and the subsequent group size is very pleasing.
I have even obscenely greased bullets to see what happened. Outside of grease flowing down the case walls and extruding into the firearm, and a plume of grease coming out the barrel, well, nothing. Greased bullets also shot well and the amount of grease squeezed down the case is enough to prevent case stretching.