So here's a wrap-up of the oustanding issues with this motherboard - mostly ok now.
The below is a copy n paste of what I just sent to Gigabyte.
Hi, This version works correctly!
There is only one minor issue. If the marvell controller is in ide mode [intel in raid] and boot is over the marvell controller, it will still fail, but this is maybe not worth chasing as most users will use ahci mode.
Maybe update the user manual with an addendum - 'no ide on marvell with intel in raid'
There are some other issues, though not all critical as there are workarounds with most of them.
1. With bios version F7, it was possible to install win 7 x64 to a raid volume on the marvell controller greater than 2TB.
At version F11 [or maybe earlier] and version F12a this ability has been broken.
There is a caveat however with version F7.
Normally, when you have a fresh drive/s and you start the computer with a bootable windows dvd in the drive, after the bios has finished post it will automatically boot the dvd drive. You will NOT see the message "Press any key to boot cd/dvd", because bios can see that there are no other bootable devices connected.
However, when the drives are connected to the marvell chip and are configured to raid, for some reason bios thinks there is an alternative boot drive besides the dvd and you do see the message "Press any key to boot cd/dvd".
If you ignore that messsage, there is a momentary flash on the screen with text on the left top quoting the bios date and version and on the right top 'press del or f2 to enter setup"
If you allow this to happen, you will find that you cannot partition more than 2tb of the raid volume.
If you DO press a key when you see the boot message and not allow the flash on the screen to happen, you can partition the whole raid volume as a single partition [with the usual small system partitons of course]
However, this is only possible with bios F7, it is not possible to partiton >2tb on the marvell chip with F12a.
No matter what I do, with F12a I always get a message that windows cannot install to this volume, when you click details it says "The computers hardware may not support booting to this disk, make sure the device is enabled in bios".
At which bios version this was broken, I don't know. All I know is that F7 works [with attention to boot message] and F12a doesn't work.
2. When installing windows to a raid volume on the intel c600 controller, at the point where your asked to load f6 drivers, only on rare occassions is the dvd drive visible, therefore impossible to install drivers from driver cd.
Workaround - put drivers on flash drive first.
3. Silverstone FP34 usb flash drive bay is not recognised by q-flash. Works fine for F6 driver install.
This never worked on any version of bios. In fact, version F12a now sees my dvd drive as a place to save a bios!!
Workaround - Ignore dvd drive and use other flash drive to save/load bios.
4. The F6 x64 drivers for the G1.Assassin 2 Marvell controller on Gigabytes website are incorrect and do not work.
The drivers on the driver cd in the floppy64 folder are correct and do work.
I have not tested the x86 driver.
Workaround - use the F6 drivers on the cd
So, the board is quite usable now, but bug No. 1 really needs to be addressed