I had lunch with John Parchem the other day. I half jokingly told him I was thinking about building a guitar out of half EIR and half Mahogany (two actually, since I have two full sets of each). Of course if I were to do this, my thought was it would just be about getting more building and bracing and setup experience, and not about producing a particularly dynamic guitar... and knowing that no one would be interested in them other than as a novelty...
Well, I was perusing the "Martin Guitars - A History - Revised and Updated" book that John Hall recommended, and what did I find?
In 1996 Martin released a limited edition guitar called the "MTV-1" that was ... half mahogany and half EIR! They made and sold nearly 700 of them, which, at least at the time, was the most successful limited edition in their history.
http://www.elderly.com/items/10U-3172.htm
I guess I'm not as loony as I thought :p