So, with my initial question, is there a way to restore B-BIOS into M-BIOS if it's not had a 'failure'?
Pretty sure my initial problems with this board were RAM related (even though it tested fine). I can re-image with Win7(x64) but I want to try reverting the BIOS image first in case the bad RAM affected the @BIOS flash (I'd updated before I noticed the reliability problems).
Install was clean no errors, no issues with driver installation, it BSODed a few hours later then every hour or so. I swapped the HDD, PSU, CPU, GPU, DVD all to no avail until I got more RAM and the problem went away. Pretty sure I clean installed the machine 1 more time before it went to work.
Hard drive diagnostic was clean. Might just be that bad flash or it's a faulty mobo or intermittent PSU.