I've got a BCM upper on a Spike's lower (bought it as a stripped lower and put my own parts in it) and haven't had any issues. It's actually my "go-to" rifle and hasn't given me any issues. All told, I have 4 Spike's lowers that were bought many years ago and have been built up in a similar fashion (stripped lower, put my higher-end parts in/on the lower) and the only issue I had was on one lower the front trigger guard hole was out of position for the KAC trigger guard I was going to put in it (could have been the TG, could have been the lower). Threw a Magpul TG in there and had no further issues.

That being said, if I were going to do it all over again with the way prices have come down since I first started building, I'd probably just order a BCM lower and be done with it.