I would describe it as more controlled and refined, compared to the stock Towers. Midrange is smoother, with less "shout", not that it was a big problem to start with.Couple of things you do lose with the mod. There's less of that "sparkle" in the top end that you get with the piezo. Might be my choice of horn, CD vs Radial. I'm playing around with crossing the piezo back in at the 8K to 10K Hz mark as a super tweeter. There's also less of that "liveiness" that the stock Towers had. I think there's a lot to be said for simple or no crossover designs.
But overall, I think its a better speaker and worth the cost. And no, I've not heard the Theater 4Pi for comparison.
Gar.