Simon,
I think the concept is cool....but agree with Andrea and Tony, that the problem would come in as to which instrument to choose. It was somewhat easier and a fairer comparison with the pianos....the sax for instance...."sweet soprano" on the Yammy's to my ear there is just no more of a realisitc great sounding sax than that and so me bringing that baggage to the table, a comparison would be useless.
I think the other thing to be considered is this......the point of it. I think originally this was just kind of a big boys peeing contest...."my piano's better than your piano." Frankly, I doubt the comparison of them changed anyone's mind from what they thought was their favorite to begin with. I know mine didn't change.
We've heard tons of the demos and stuff now and everyone always says...."it's much better in person" which is no doubt true and I think any of us following all the boards have heard pretty much every board there is by now and unless we're doing it just for the heck of it......
jam on,
Terry