Sorry can't speak to the comparison factor, though can 2nd the value of the thread golfugh recommended. The info provided by funkmonkey, craigsub, & nuance over there, along with the general info here regarding Jim Salk's work were the basis of my Song Tower choice a year ago. Happy as the proverbial pig in slop with that decision.
If you're looking at primarily 2 channel, I'd recommend checking out the new AVA Insight Integrated to match with the STs in particular. My 2 channel is separates as I had Frank convert my old Hafler 220 into a Hafler 250EX (effectively the OmegaStar 260EX), were it not for that I'd probably have given the integrated strong consideration. The combination if you wanted Frank's remote control (recommended), depending on finish choice on the Song Towers would bring you in pretty much at your max budget, but I don't think you'd be disappointed on any level.
I also figure there's a reason Jim & Frank team up at RMAF, and other shows to showcase their wares, aside from regional loyalty. I believe there is a definite compatibility factor or much as I cringe a little at the term, synergy, with their respective products.
If you haven't already you should check out the Salk section here, 'Owners willing to Audition' thread. Not sure where you are, but you might find someone close enough with Song Towers to give them a listen. If there's no one listed in your area, post a inquiry.
Good luck in your search, and have fun.