Spacekadet,
Thanks for your question. Unfortunately, no, I haven't heard the ACT2. Although I have extensively heard the new carbon fiber ACT, and it is one of my favorite speakers. Compared to the Curves, it has a bigger, more open sound, better extended bass ( although not deep bass ) and the ability to image a little better. When properly positioned,
the imaging of the ACT is magical ( without sounding bright). Norah Jone's "Lonestar" just floors me. She is perfectly positioned in center stage and the surrounding musicians have so much air between them, I feel I could get up and walk around the band members. The only other speaker I have extensively heard with that same effect is the Peak Consult Empress. I'm sure that you know that the ACTs are 2x the price of the Curves and the Empress is 2x the cost of the ACTs.
I have always felt that my Curves had adequate bass but not deep subterranian bass. I've tried to incorporate a REL Strata III into my system. Unfortunately, I can't get that darned thing to properly integrate with my speakers. This is probably due to my room. The sound is okay in the sweet spot, but I get a bunch of other places in my living room where the bass is reinforced. These "nodes" really drive me crazy. I have even considered adding Bryston amps to help with the bass. Finally stumbled on a solution when I added the MF XDac, X-10, XPSU between my CDP and my amp. These little boxes noticeably extended and tightened up the bass. Sam Tellig was right...go figure. Please keep in mind your room when choosing a speaker. The Curves are more than adequate in my living room ( 18'x 30' ). The Curves also have adequate bass for the music I listen to. Good luck on your search. I don't think I've directly answered your question, but I hope this helps.