The biggest reason I went with a big rear sway bar was to loosen it up - introduce some oversteer. The 6s have a lot of understeer - much more than the GTs or Cobras. Mostly due to the lack of weight in the front end compared to the bigger motors. Since the contact patch is bigger in the rear than the front, that off-sets some of the oversteer created by the larger rear sway bar.
I think the next steps for me at this point is to change the bushings, add subframe connectors, and a G-trac bar. I'll probably change the end-links as well. I'm not convinced yet that a strut tower brace does all that much - maybe in really heavy cornering it might help a little, but compared to the other issues that need to be addressed it's kinda low on the list.
I did notice tonight that the rear end jumped around a little under hard cornering - probably too much lateral torsion on the rear axle. I should find some way to deal with that eventually, too.
Of course, I should probably just stop screwing around and do an IRS swap like the really cool people...
If you don't mind my asking... what did that cost you? I assume you did it yourself - or did you have someone else do it?