Chappy - As far as reloading equipment/dies are concerned, you have to make up your mind what is going to work for you. No one can tell you that this is best or that is best for you. If you ever decide that you want the Competition seater, you will get spoiled, it such a convenience. Notice that I never said that it makes the most accurate ammo. I think they make good ammo, but there are better choices if you are going for ultimate accuracy. I do not think that very many bench rest shooters use them.
I really like the neck collet dies. The number one thing is you need no lube what so ever. The way the die works, it squeezes the neck back down to size, so no lube is required. Second, it does a decent job of keeping the neck straight. The stem reaches all the way through the case and centers in the flash hole. This keeps it centered in the case so the necks are concentric. Of course if you have cheap cases and the flash holes are off center, then it will cause some case neck run out, but still not a whole lot. I have found that if you stick to good cases, Winchester, Remington and of course Lapua and Norma cases you do not have a lot of problems with off center flash holes. Having a case neck concentric and straight is the key to seating bullets with out or little run out. I have 3 223's. One is a H&R Ultra Varmint and the other two are bolt guns. I keep separate cases for each. I have many plastic boxes and label each one for the rifle it fits in. I have developed different loads for each any way. I then run just their own batch through the tumbler and keep them separated through out the loading process. I then put them back into their respective cases. When I grab a certain rifle, I grab a box of ammo that matches it. I only full length re-size when I have to. By only full length re-sizing I extend the life of the cases and I have more accurate ammo to boot. I really wish I could get a die from Lee for the 221 FB.
victorcharlie - No one has mentioned the L.E. dies, because the question was about RCBS Competition dies. But since you brought it up...The L.E. Wilson dies are by far the Bench rest shooters choice. Second choice is probably the Redding Competition Seating die. But at $80 for the Redding and $80 for the L.E. Wilson Stainless Micro seater they ain't cheap either. With the Wilson you need an arbor press, not a regular die press and is a much slower process, but good however. I do have a Forster Ultra Micrometer seater and I think it makes slightly better ammo than the RCBS. But it is caliber specific and it is not as convenient as the RCBS, you must feed the bullets in from the bottom as conventional dies do. They are in the $57 range.