Used to go with the RCBS for a long time, but now just use the lathe with a single point HSS cutter, with the pilot for the case neck that extends through the flash hold as well.  The glitch part that I never liked on the RCBS unit, the pilot was spinning in the case neck, with the cast stationary instead.


Hence as you are turning the case necks, you don't want the case to wobble on the pilot, which will cause the necks to peen/enlarge, which will cause problems again with the necks not uniform in thickness when resized back down again.

So since I have the old style screw type collet on the my RCBS trimmer


It's taper collet holder gets chuck in the lathe jaws, a long draw bolt is used through the spindle to lock the case in the collect, and have next pilots that look somewhat like the Lee trimming rods without the stops that I lock into the tail stock in a live end to support the case.
Hence as the case is turning, so is the pilot with it as well.  Also to note, when sizing the brass, will not use a expanding button, but let the trimming pilot enlarge the neck ID to it, so there is a tight fit between the pilot and neck of the case for neck turning instead



As for my cutter, just a piece of HSS drill rod in a block that is sharpened to a razor point to turn the necks.  As for sharpening the drill rod, just chuck up my taper diamond wheel in the chuck, which makes short work of bringing the tip back to a razor sharp point.
Note, the same way I make threading tools as well, hence just set the bit high against the wheel, and will taper the front of the cutting edge downward as well.



Simply, you can go fast with some of the hand tools on the market, but you can score a used mini lathe for the same amount as your going to spend on tooling the hand way, and end up trimming just as fast, but a lot more precise with the mini lathe instead.
Note, I set the lathe to move the cross slide towards the tail stock, so a snap to trim brass with a very slow feed rate, and don't have to hover over the machine during the cuts instead, since there is room on the pilot in the live end to over cut and run free for a ways before the cutter will crash into anything.

It slowly advances the cutter up the neck as you are wind the handle to leave a cleaner cut, hence auto feed system.

http://www.brownells.com/reloading/case-preparation/neck-turning/neck-turning-tools/case-neck-turner-attachments-prod37394.aspx

Hence without the auto feed, guys tend to rush case neck turning, and just make a mess of it instead.

PMA

Not really, since if you are unifying the cases for say bench rest where you will not be bullet crimping, then prep includes removing the ID neck donuts shoulder of the case if there are any after firing forming if you are going to seat the bullet past the donuts.



As for Plan Jane ammo in a plan Jane chamber/rifle, then bullet crimp alone will have more tension on the bullet over all than anything else, plus the chamber neck area is on the larger side anyway compared to factory formed brass, so some case prep may make sense, while going to effort of full case prep with donut removal reaming and even neck turning (less than the ideal way to make a mess of isntead), may not yield any differences isntead.

Will agree with you for most shooters, but you have to group bean field shooters/long range  hunters shooting long shooters, into the bench rest group as well (guys running 40X/built rigs that are capable of .5 or less groups and pushing plus 600 meters shots as the norm.  Also as pointed out, when you are forming cases out of parent case where the necks of the new case will be from the side walls of the old case, then neck turning is required most of the time to reduce the neck thickness as well.

Fact it, there have been plenty of 10 rounds groups in .09 MOA  and smaller groups @ 100 yard  shooting indoors, over and over again as the norm, where wind is not a factor.   So if this is your goal (Holy grail you are chasing), then the only way your going to pull such off is with the cases all being unified down to the last detail to start with.  If you shooting 1 to 2moa with a production rifle instead, then any major case prep to unify the case to a precise uniformity is not going to reduce such way down, and the minuet differences may not even be noticeable instead for the effort put into this amount of case work.

So having said this, and you do need to turn case necks, then think long and hard on the tools that you are going to use.  Hence once you start breaking the $300 mark, then you into the same amount of money for a small  mini mill that is like new in box, which will have other purposes than just turning case necks alone.


FYI for those chasing the holy grail, Record .009" group, and shot outdoor as well.
http://www.outdoorlife.com/blogs/gun-shots/2013/05/benchrest-world-record-jim-carmichel