> Therefore, my impression that the installers do not install something "by mistake" and try the booted disk first still stands.
I agree that installers try the booted disk by default, but I can't argue with ganbustein about the "by mistake" part; he's got too much history to my too little.
Apropos of that, did you see his "The App Store application [...] update(d) the copy of "Install Mac OS X Lion.app" that I had squirreled away on a different volume where I thought it would be safe?"
