The alternative of course is to do only crossbuilds. Is it reasonable to say that, for platforms where a bootstrap is no longer feasible, a successful crossbuild is an acceptable test procedure to use instead?
Sure, and get flamed and trounced by Uli on glibc when you talk about problems with crossbuilding.
He'll flame you anyway for talking about platforms that are no longer relevant to the desktop. (Well, maybe he wouldn't. See http://lwn.net/Articles/19297 )
A successful crossbuild is certainly the minimum concievable standard. Perhaps one should also require bootstrapping the C compiler alone; that would provide at least some sanity-checking.