Followed Stork's instructions completely and went without a hitch from 10.9.1 -> 10.9.2.
Tested USB 3.0 external drives a few times without any hangs so far as some reported.
Z87X-UD4H, i7 4770k, intel onboard graphics (for now), Kingston hyperX SSD
EDIT: I'm running BIOS version is F7. F8...