I had the same question a while back and one comment I got was that, since I do not have the angel yet, to get the SPS first and let them stablish themselves in the tank, then get the
angel fish. The reasoning was that the fish being the newcommer to the tank will be adjusting to the new sorroundings as opposed to getting the SPS after the fish because it may go see what the new thing taste like out of curiosity and then develop a taste for them.
Also, according to this lady, some angels fish have a wide mouth (
potters angel) and some have a more pointy mouth (cherub); the ones with pointy mouth are somehow more likely to nip. I do not know if this is true or is just coincidence.
I realize this is not your situation but I tought this may help someone.