Just received a mini 9 from Dell UK. Amazingly when I checked the BIOS it read A01 - do they really not bother updating these things at all in the factory?
I figured since I had a completely clean install of Windows, fresh out of the box, there was a relatively low chance that the Win BIOS updater would screw up or crash so I took the plunge with it.
What a bloody nightmare few minutes that was. The win flashing app started up, reporting itself to be 'not responding' then recovered, then switched to a completely white window with no UI and reported itself not responding again, and then the mouse froze and the machine wouldn't respond at all. Fortunately I have a personal rule with critical stuff like this to leave it for at least 30 minutes before doing something drastic like powering down. After about 5 minutes it restarted and when I checked is now reporting A04. So, it works, but be prepared to suffer for it.