DLC gives a superhard coating that helps lubricity (action feels smoother/slicker), but doesn't necessarily help that much with corrosion protection.
Cerakote will hurt function until it wears in (gummy, sluggish, while you're wearing through it on mating/sliding surfaces). CKote, however, is outstanding for corrosion protection, and is a pretty tough finish in general. Once it wears in it's typically no worse than a standard action (no finish special coating/finish).