Rather than merely echo the comprehensive wisdom of the thread, I'd like to observe that the Eigenharp is a wildly impressive alternate controller, yet the demos always seemed to be ambient or known show-off items, such as the oppressively overused "On The Run" loop. I like the concept, which is alluring, but do you see anyone playing an Eigenharp, anywhere? No. Its too boutique-alien and most people can't connect the act of playing it with the resulting sound. That could have led to a wild new genre with an expressive core, but if you can't get people to grasp your language, your poetry is still going to sound like a rave for crows.
I'm hoping MPE will keep its footing, but I'm still waiting for someone to wail on it in a manner that makes enough ears perk up.