Jay,
I have a 2010 4B-sst2 with all the latest and I have a 4B-sst with a 2005 date. I spent a full 8 hours recently comparing the two amps. Associated equipment included Martin Logan CLX speakers, Acoustic Zen wires and interconnects, Meridian G68 processor, Meridian G98 player and a dbx driverack 260 to split the signal. My conclusion: I have more respect than ever for the 4B-sst. Even though I give a slight edge to the squared, I will also keep the 4B-sst as the power to the side speakers in my primary Las Vegas system and I will put the 4B-sst2 on my mains in Los Angeles. IMHO you have a great amp. Congrats on a good choice.
Gary