Ahh...
As far as I know the relative position of "main vs center vs surround" is important when encoding but the relative position of woofer vs. tweeter in the same speaker is not important.
The idea behind turning them upside down is just that high frequencies are more directional than low frequencies so having your ears not centered on the woof/mids won't make anywhere near as much difference as having your ears not centered on the tweeter.
I always ran my speakers upside down whenever I had to mount them high, always felt that was better than the alternatives.
My M60s are right-side up 'cause they are on the floor, and the M2s are right-side up 'cause I finally have stands of the right height
