Hey Pat, I resemble that remark!!!

Actually CST is the only company I have come across that sells the stuff. I have never used it myself, but a friend of mine owned several Terminators and X-Terminators, the wings were molded using Rohacell.
I was not very impressed with the way it withstood even minor damage. The spars could break loose from the inside surface very easily if the wing was torqued in a less than perfect landing. It appeared to me that even though the bond between the spar and the inside glass surface was very good, the rohacell was able to crush just a tiny bit and that allowed the thin glass on the inside to crack along both sides of the glue joint. The spar, glue joint, and the thin strip of glass that it was attached to seperated from the rohacell.
I think 1/16" balsa would be just as good or better, and at much less cost. But that's just my opinion, I could be wrong.