Re: 308 dies
"What I have" is meaningless, what I know about all brands of dies is meaningful. I have some 50+ die sets in more than 30 calibers by at least 12 makers, some long gone; they all work fine if I do my job, none do well if I don't.
Fact is, most chambers are reamed with a SAAMI standard chamber reamer. Most sizing dies are reamed with a reamer ground to SAAMI ammo standards. Those standards do not overlap and all of the standards are a range, not a spot measurement they aim for. The result is there's very little slop between our chambers and our dies. That means even at a worse case scenerio there's precious little accuracy to be gained with a custom made sizer for any factory rifle chamber. It also means there is about the same average difference between dies of the same maker as there is between makers.
Seaters are a bit different. The threaded 'straight line' seaters by Forster and Redding (only) virtually duplicate the results of costly hand seater dies such as Wilson and copies. But NO seater can seat straight in bad case necks. Most case necks are much less than perfect so the loaders skill and methods to insure quality brass is at least equally as important as the seater he uses.
Bottom line, get a die set that costs what ever it takes to make you feel comfortable and use them. It takes a long time for the skill of any loader/shooter to exceed the accuracy capablility of common dies.