Don't know what "negativity" you might be expecting from that arrangement, but although it should certainly work, it would seem to be redundant. The QS8s have exceptional horizontal and vertical envelopment by design and it would be unnecessary to arrange two of them vertically.

I have read good things about them. I'm quite exited to make the call but it'll have to wait another month or two.
I am a fan of where surround technology is heading and thought it might be possible to get ATMOS type surround (similar not equivalent) from a typical 7.1 setup.

a few beers later it sounds like dumb idea.
when/if I try I'll report back. ;-)