Rlw3,
I hope you will get a chance to listen to a GAT before you sell the ACT 2s2. I think "some" may prefer the ACT. It's getting pretty personal at this level. Even the speaker of choice may lead you to preferring one over the other.
I have not heard the GAT but hope to one day. I have found the TOTL CJ preamps to be "best of breed" for me. I do own their ACT 2.2, ART 2 and ART 3.
My systems are balanced to my satifaction now. Could it get better? Maybe. The one thing that gives me pause about the GAT is the solid state (mosfet?) buffer stage. Even though it's not technically a gain stage (good thing IMO), the signal still goes thru it. I have no doubt that the GAT is a world class preamp but I just don't feel the need to make a change.
So, you may prefer the GAT over your ACT and so might the vast majority but I always remind myself when reading opinions/reviews: 95% may prefer the GAT, I might be in the 5% that hears the ART/ACT 2.2 as the better preamp.
Good luck. If you ever get the chance to compare, please let us know what you think. I'd personally be interested.