I've just got the Nature paper. Microraptor has distally placed and long halluces (both more so than in Archaeopteryx), but they are definitely not reversed. Of course, I can't judge whether it may have been revers*ible*, and preservation is another issue...
BTW, what arguments are there to exclude alvarezsaurids from birds? The prokinetic skull of Shuvuuia seems clearly avian to me.