I can compare Heresy (III's) to RF-5's, but not RF-52's. If you have a sub, go with the Heresys. The Heresy''s have slightly better mids and highs. They drop off fast on the bottom end however. The RF-5's are almost as nice in the mids and highs but blow the Heresy's out of the water in the bass dept. If you only have room for 2 speakers, go with the RF-5's. If you can work a sub in, the H3's are the way to go. BTW, they're both great speakers and I'd have no problem with either set.
Carl