I didn't build it myself, but I bought an upper recently specifically with the NiBX BCG so that it would be easier to clean and more reliable in the long term. I used the general phosphorous BCGs back in the day and they were a pain to clean, especially the rounded backside of the bolt. Unfortunately, I've had some problems with this upper where the bolt doesn't seat fully forward sometimes when I load a new mag. I pull the trigger and get "click." I attempt to charge the charging handle but it gets stuck and I have to mortar the rifle to unseat the bolt from the star chamber. In every case, the round has been good (i.e. it's not a bad primer or something), and I can't figure out why the bolt gets stuck in the chamber. I believe part of it is that there appears to be a little more friction between the bolt and carrier which, when combined with other possible factors, adds enough resistance to prevent the charging handle from pulling the bolt back. The NiBX BCG is great to clean but I haven't been sold on its reliability. I've also read that other people still have to lube theirs. Other issues might be creating the particular problem with my rifle so until I figure out exactly what it is I can't say for sure that it's the NiBX coating. However, I'm hesitant to give it a thumbs up as worth the additional expense, unless you're willing to spend more to just make cleaning easier.
The state that too strictly distinguishes its warriors from its scholars will have its fighting done by cowards and its thinking done by fools.
Kahr PM9, Springfiled XD9, Browning BPS 12Ga., Browning SA-22.