I'd take a system like that any day. Except that price is... out of my range. I value CPU speed far more than GPU. Why? Because Apple has made it perfectly clear they dont give a crap about proper GPUs. The only GPU need I've ever had was for gaming, and because of the limitations for so many years, I've pretty much abandoned all gaming on my computer.. which has now left me not giving a damn about the GPU. My work relies on Photoshop, Illustrator, Indesign and some After Effects. Not much of a need for two FirePro video cards or a FirePro GPU of any kind. An AMD 270X for roughly $200-$250 would be perfectly fine. Less heat too from a single card.
It should be mentioned that the FirePro D300, D500 and D700 all equate to roughly the W7000, W8000 and W9000 which, on Newegg.com each cost $700, $1,400 and $3,400 as a SINGLE card. Apple puts in two of each. Needless overkill.
Your work revolves around the Adobe suite and you don't see the benefits of the GPUs? Even after Adobe's commitment to OpenCL?
Also, even though the specs are similar to the W**** line! it's highly unlikely Apple is paying anywhere near those prices.