MD, I'd just be guessing, of course, as to how each setup would sound in your room, but be that as it may, my preference would lean toward the height of the wall mounting rather than the symmetry of the mounting on stands. Keep in mind that the mid-woofers, which handle the majority of the sound, fire up and down, so that will be identical for both speakers in your proposed wall mounting. The tweeters will have different dispersion paths, but my thought is that the difference at the listening position wouldn't be very significant. Mount the left surround on the closet wall as far to the left as possible, to match the right surround in at least that respect.
