I recently installed 2 blue pop 24" as part of my 6 bulb setup. I placed them in the dusk/dawn slots. So now I'm running front to back:
Coral+
Blue pop
Blue+
Blue+
Blue pop
Coral+
I replaced two blue+ out of my dusk/dawn slots. I feel they are slightly dimmer but Certainly give the corals a certain pop I was looking. As of now I'm happy with them and saved me from buying reefbrite xho's.