Successfully tested ATI Radeon 5870 Eyefinity 6 and vvvv with following configuration:
ATI Radeon 5870 Eyefinity 6
Intel Core I7 2600 3,4Ghz
Motherboard Asus P8P67
8GB DDR3 1600Mhz
1TB SATA2 7200rpm
Datapath VisionRGB-E2 Video Capture Card
Datapath VisionSD4+1 Video Capture Card
Windows 7 Home Premium 64
Connected 6 display outputs:
1 VGA monitor
4 projectors (1024x768) grouped (span mode) with vvvv multiscreen edge blend
Used Apple Mini Display Port to VGA adapters
ATI Radeon 5870 Eyefinity 6 can use 2 outputs with passive adapters (DVI / HDMI) and the remaining 4 outputs must use active adapters. For Mini Display Port to VGA adapters I guess there are no active adapters since you are already converting from digital to analog. Used Apple Mac mini DP to VGA adapters successfully.
Very easy to group various combinations of outputs (span mode) as well as select different resolution and orientation settings for outputs. Monitors / projectors must be plugged in to be detected.
vvvv performance very good with this system.