That 8 board stack is about the same hashing power as a 3 unit Avalon.

Are you using a RasPi to connect them to the internet?
Wrong. 8 bb boards = 160 chips. Each avalon module is 80 chips, so my stack is equal to 2 avalon modules.
For now I am using Ubuntu 12 and cgminer 3.3.2.
I have the Raspberry too, just didn't have time to set up a sdhc card with the software.