I wonder if a fan-spacer card would be good. It would pass SPI and use power for fan(s). This would be great for someone with room to alternate cards...
I wouldn't want to use a slot for non hashing equipment if I was full up. I think there will probably be lots of cases available for these units. At 8k for 400 GH/s they are going to destroy BFL. I am looking forward to the December batch (or whenever) when I am ready to go full tilt for a couple of TH.