I have the Hornady 454 die set with titanium nitride sizing ring. It works great. The coating has to be applied correctly, but once done, it will not wear out from any amount of brass cartridge resizing. I've heard they had some problems with it when they first started using it, but not with recent (last few years anyway) production.
I really like their seating dies best. They combine the sliding alignment sleeve of redding and forster competition types, with optional micrometer adjustment for any seater die they make. And they disassemble while on the press for cleaning without affecting the settings. That is a real plus when using lead bullets, since the lube tends to gunk up the works after a while. I simply pull the clip at the bottom of the die, and the sleeve and seating punch (everything that comes in contact with the brass or bullet) drops out the bottom.
Andy