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.
Equal in number of chips. But the chips in the Burnin boards have higher overclocking potential, therefore more hashing power than the same chips in Avalon modules.