I've got the bug to upgrade my old RT800 and CS400 Polk speakers.  What I'm curious about is the sound differences between the 5T and 6T speakers (I know the public has not heard the 6Ts so for now, just looking at the theory).  My low frequencies are taken care of by a pair of SVS PB12-NSD's in an approximate 5000sqft room (28x21.5x8) plus a small hall (20/80 music/HT).

With the same tweeter, the upper frequencies should sound very similar.  If the lower frequencies are taken care of by the subs, is there any advantage in going to the 6T (crossovers are currently set at 100 Hz on the receiver) over the 5T (which looks good down to 80 Hz)?  Am I acutally going to get a better sound out of the 5Ts due to the 5.25" mids?