Upgraded everything but ME to the latest via UBU with complete success, but the part folks might care about:
If you were experiencing the issue with RAID 5’s dropping on reboot while using the version 3.5 OROM and 3.8 drivers, upgrading to the 3.8 OROM resolves the issue and keeps TRIM working.
(Not comfortable making a public offer on the BIOS, especially since I didn’t upgrade ME - but if anyone does want it feel free to PM me.)
Thank you both Fernando and SoniX for your help.