I've never seen or heard them in person, but I've read about them in my quest for ideas.
I have heard Magnaplanar speakers and they are quite remarkable.
I just found it hard to get over the fact that you need 500W/ch. to drive them!
I also don't like the idea that they are SUPER sensitive to room placement.
That's why I put together $30 worth of full range drivers!
The lines are crossed over at about 120Hz.
The horns are crossed over at somewhere between 600 and 1200Hz. I'm not really sure... I have to tweak it for a couple of weeks before I give up and leave it alone.
I have not had the horns in the living room powered up for about a year! They've just been sitting there, silent.
James.
BTW I made a crossover on a proto-board with op-amps that is 24dB/oct at 113Hz for the sub woofers in Metal.
That was my first experience with bi-amping. The 12 inch aluminum cones are in a 10 cu. ft. box. They're -3dB at 14Hz!
http://www.akrobiz.com/speakers/metal_index.html