I bought one of the Hornady Lock-N-Load Bushing conversion kits a while back for my Rockchucker and have been extremely pleased with it.  I was tired of having to set up my dies every time I switched them.  I had locking rings with set screws and had marked them and my press for indexing purposes but I float my dies on an o-ring and this sometimes caused issues with being able to repeatably set up dies.  I bought these and a bunch of the bushings and never looked back  I set up the die in the bushing once and I'm done.  Next time I use the die I drop it in and the bushing locks into place with about 1/8th turn.  

Most importantly, I have found this kit doesn't hurt concentricity in the least bit!  I'm still producing rounds with less than 0.002" runout.  The only difference is that I'm doing that from the first round to the last whereas before I would often have to tweak the die slightly when I first set it up in order to get that low runout I'm looking for.  These effectively ramp up the efficiency of your single stage loading to that of a turret press.  

On the Rockchucker you just removing the black insert that your dies screw into and screw the new Hornady sleeve in.  All your dies will now need to be mounted in bushings to work with the press but they're not that expensive and well worth it in my opinion.

Link to the kit on Midway

Just thought I'd mention it in case some of you haven't heard of it before.

DOC

I've been considering this system as I load a number of different calibers and switching/setting up dies is a PITA.  

Good post, OP.

Picked one up Saturday while I was at Fin Feather and Fur in canton.

Going to try it out tonight.

I run a LnL AP, so it makes nothing but sense. Other then when I use a dillion case trimmer.

It really is the shit

http://www.ar15.com/forums/t_6_42/386575_Upgrade_to_my_Rock_Chucker_using_Hornady_LnL_bushings_.html

Love the conversion on my rockchucker.