It appears the BFGMiner definitely has better performance in terms of what it's reporting to the pools, but it's still a bit slow.
Within the miner I'll get 660-680 MH/s, but only about 580-600 are getting reported by the pool.
This is observed using MacMiner 1.3.17 (which may not be the latest build or official release version).
In MacMiner, the FPGA/ASIC miner works great except that every once in a while it'll just stop. I can set up a notification for idle workers but it always happens when I'm at work and can't take the hour round trip to restart the buggers.

Hopefully the BFGMiner will run with greater stability, even if I'm losing several dozen hashes/second. Better that than huge swaths of downtime.