I experimented with BCLK overclocking twice trying to aim for a +100 MHz increase on the CPU, both times something went horribly wrong.
Attempt #1: Bumped up BCLK from 100 to 103.5 MHz for a 100MHz CPU overclock, dropped RAM frequency from 1866 to 1600 MHz. Neglected to undo my previous CPU undervolt (-60 mV core, -160 mV cache), and my system refused to POST.
Attempt #2: Limited BCLK increase to 103 MHz, lowered RAM frequency to 1600 MHz, and used stock CPU voltages. System posted, but my second display refused to extend my desktop and duplicated the first display instead. Windows Aero refused to function properly, and everything was glitchy overall.
Overall, it seems the costs of instability from BCLK overclocking far outweigh the limited benefits.