Harsh reality; Apple has it's work cut out for them. The Mac Pro is a beautiful machine, inside and out but it needs to be updated. Perhaps a video editing-specific model should be introduced to compete as opposed to Apple's Mac Pro "Swiss Army Knife" marketing approach.
I realize that this is just one test, but it's my understanding that Final Cut is still 32 bit, so I doubt that a Final Cut export benchmark would make the Mac Pro look much better.
I come from an office where both Macs using Final Cut and PCs using Premiere CS5 were in service. One day on show site, a long time Mac/Final Cut user's jaw dropped when he saw me import an s-load of Panasonic P2's and they became immediately ready to edit. No Log and Transfer.
Do you really want the rest of us paupers to drool? I`ve got most of that stuff and no mentionable money. For the money, you could use a set of hard drives and other hardware to "Hackintosh" your AMD, use a second set to Windows your same AMD, and a third set to isoLinuxize, usually Ubuntuize a suite. Crank out the usual sandpaper- quality shows out of the first one you get going, and save money for the Mac Pro, even if the AMD Hackintoshes well. Could means no guarantee. If you get a software shutdown, it`s usually rejected hardware like unsupported audio or video cards, or an adjustment.