I had my Heresy on my LaScalas in the MTM configuration for a while.
One thing that isn't getting a lot coverage here is the different and potential sound shaping, after market crossovers which you can typically find on Ebay. Some of these have gotten so successful the makers are now building entire Klipsch like speakers (the bigger ones). Do a search for Klipsch crossover and I bet you'll find him, and the other crossovers makers around.
I still think you need a lot more power than it appears, because the squawker gets loud first and you think hey the volume is up, what's more power going to do. It is loud but the woofers just don't get going without some juice.
Finally, get your hands on an old McIntosh power amp, even the smallest old SS model MC 2505- I think, mine is in storage. It has only 50 W per but each channel has a gain knob so you don't need a pre. The McIntosh house sound works great with Klipsch. I won't say why because a lot of people get their hackles up over it (OK -I will tell you why, they they tend to be warm imho)