Does anyone use the M50 or M40 for surrounds?

I have owned the M50's and although I never ran them as surrounds, they would work fine.

Wow, that'd be some system running those towers as surrounds.

I have tried using mains or other bookshelves as surrounds in the past, and they work well. However, I do prefer the enveloping ability of the Qs8's, as they truely Surround you in the action, and you don't have to be in the sweet spot to get the full benefit...just my 10cents