I've got the GA-990FXA-UD3 running BIOS F5 -- there is a beta F6 floating around.
In order to avoid frustration you should flash each chip of the dual BIOS with the same BIOS version! It's a simple process found in the manual or lookee here
. It will make tweaking much more enjoyable.
Everything works just dandy. I run 2 external 5-bay HDD enclosures off the 2xeSATA using the port-multiplier. It has unlocked an X3 Rana and PhII 555, and clocked a PhII 965 to 4GHz+ without difficulty, in spite of an Antec Earthwatts 650w with a ripple issue. I haven't Crossfired anything but I assume it will function as spec'ed.
I boot to an OCZ Agility SSD in less than 20 seconds -- it's got plenty of fan headers. I can't speak to the thru-put of the USB3.
Early revisions have VDroop and don't offer LLC -- fixed in updated versions. I'll wait for BD-II and a serious price drop in a year or so before going AM3+.
Sleeps at 5w and wakes without issue -- I'm using it to stream media ...