The NiB coated BCG's such as WMD Nickel Boron BCG are a nice upgrade. They run smoother, clean easier, and need less lube to operate properly. For the average coyote hunter, IMO, it wouldn't be a NEEDED upgrade for a real low round count. However, it is a worthwhile upgrade if you like the benefits of it. Just pulling the charging handle back you can tell the difference in a blind test, honestly. The dry NiB BCG will be smoother than a lubed phosphate BCG.
Just a different twist. For the price of that bolt you can get your whole gun tefloned by BlackIce. You just wipe the bolt off with a rag as nothing sticks to teflon. I have three ARs done by Lee.