I just updated to the newest BIOS, 1.2.1, and it's improved nothing while managing to break suspend/resume.
Where can I download a copy of the last BIOS?
For anyone else who wants to revert:
First, I can confirm that it is possible to cleanly revert to 1.2. Thankfully.
Here's what I saw with 1.2.10:
1. Suspend/resume does not seem to render the backlight functional. You get a black screen.
2. Backlight control is somehow broken, even before suspend/resume. This can be somewhat fixed by using acpi_backlight=vendor.
3. No change to the Thunderbolt stability. It still dies after a suspend resume cycle. Since the screen was black on resume, this was verified by ssh'ing into the machine.
4. BIOS still corrupted after a resume (dmidecode works before suspend/resume, shows corrupted table after suspend/resume.)