I have used SPC and EXG on strats fitted with BKPs with no ill effects.
I only wish that the pot worked backwards on these so full up is normal tone and you have to roll it back to make an effect change - since I am so used to making sure everything is on 10 for normal playing.
I am keen to try the RPC at some point to give a more cutting edge to a fat humbucker for soloing tones.
Not sure if they do anything to the output impedance of the guitar though - although that will mean you get less treble loss down a long cable.
I know that the Afterburner and PA2 (both of which I have used with BKPs) apparently do that.