Hi Mike. To answer your question, I have never run out of power with the Horn Monos on the La Scalas, and I've gotten them up to "pictures falling off the wall" levels regularly. The Rogues had more current swing and slam (120 watts a side can do that for you), but the Horn Monos also go very deep and with great authority. I listen to heavy metal, space rock, dub reggae and electronic music mainly, and never lack for volume or impact with the Horn Monos in my setup. I haven't looked back from the Rogues, which I never would have let go if I had any inkling that the Quicks were close on headroom.
I think your idea of trying the horn monos on the fortes is a good one - though bear in mind the horn mono is lower gain than your mini mites, and the forte is lower sensitivity than the la scalas I'm using. How much headroom you'd have, I wouldn't be able to say (but in my setup, I can't see the end of the tunnel, so at 104db, there's plenty.) I sold my Forte II's about a year before picking up the Quicks, else I'd be able to tell you firsthand!