I haven't switched from the F9394, but I did switch from the DT029 to the MY171, the installation went flawless. The only problem was that I bought the MY171 off of ebay, so I didn't know what BIOS Rev it had on it. So not thinking I installed the dual E5335 quads, and went to boot it up and it ended up having BIOS Rev A04, which did not support the quads. So I had to tear it back down, put my dual core back in it, boot and flashed BIOS to A08. Tear it back down again and install the quads. But with A08 it booted into windows without a problem.
After all that though, I recommend first installing just one dual core and 2 GB of ram just to boot the new board to check the BIOS Rev number and if you have to flash it, flash it.
But yes I searched everywhere and no one clearly had said they switched boards just to support the quads, but with the prices it's definitely worth it, and I was not going to fool around with all of the little tricks just to get quads to boot for a little while.