*but*, there *is* one ting that thiels *cannot* do well that hasn't been mentioned: they make wery poor nearfield speakers. this is due to their 1st-order 6db/octave x-overs, & their relatively large (vertically) front baffles. thiels need lotsa room around them, & ewe should be *at least* 10' away from them for the sound to properly integrate at the listening position. then they will sing, w/acoustic, electronic, or any other music ewe throw at 'em.
bottom line - wait 'til yure in yer gnu listening space, where they can be properly set-up, before ya make any system changes. your gnu space should work fine, w/the possible caveat that, at 12' wide, i'd recommend sound absorption treatment at the 1st-reflection point at the side walls. if ewe can treat the ceiling's 1st-reflection point, this wood also be helpful...
regards, doug s.