My experience-
About 10 years ago, I bought a heavy barrel Remington 700 Varmint in 22-250 as a PA woodchuck gun. Gun shot about 1 inch with various factory loads. When I had acquired enough brass, I went to my local gun shop, who only had 55 grain Sierra moly coated bullets in stock, so figured I'd try them over H380 powder.
1st load out the door averaged between 1/3 and 1/2 inch, all day long, so I went back and bought 2000 of those bullets, and have stuck with that load combo ever since.
More accurate then non-coated? Don't know, as I stopped experimenting with that rifle after trying the above load. No doubt, if I tried other bullet / load combinations, I would find one just as accurate in that rifle, just didn't see any reason to.
Faster then non-coated? Maybe, but according to the chrony, there is probably more variation in velocity between individual guns then from just the coated bullet itself.
Barrel damage? I clean that rifle with Hoppes #9 and a brush after every 50 or so rounds, and have never had issues with rusting, or Moly build up effecting accuracy.
Larry