Looks like it'd work, but a few concerns.
I wouldnt run the SSD and HDD through that. I understand that the performance would be affected for starters, but also I dont think it'd just 'work' as they do straight onto the mobo. You generally have to use extra software to configure cards like this and Im not sure it would support a boot drive. Finally, wouldnt it block one of the fans on the graphics card?
Would the SSD through a SATAIII port on a PCI card be slower than just using SATAII on the motherboard?
This whole extra software thing sounds like a pain too, and if it can't support a boot drive, then it's seriously lacking a basic feature.
It would have about an inch or more of space between one GPU fan so it would block some airflow for sure, however my friend's set up is fine with the top ASUS fatty being blocked by the bottom ASUS fatty:
So if that works for him then a shorter, further apart PCI card ought to be fine.
the PCI-e bus is usually near saturated with a graphics card or two. I certainly wouldn't want to be giving up PCI lines to duplicate functionality that your board already includes.
I will never go down the 2 graphics card route. I can't think of anything else I might wish to use PCI/PCI-e slots for in the future either, where as I do need more storage space, and unless I just get a new Nvidia card in the summer which is slimmer than the ASUS fatty (sold to fund purchase of said Nvidia card of course), freeing up two more SATAII ports and maybe even the SATAIII ports then besides ghetto cable solution I can't think of other options I have?