This is a very good device, with small size and. I would buy this thing, if I have the money. And after reading the FAQ, I found that this thing could mine Bitcoins...
You could leave a raspberry pi running for all eternity and it will never 'hash together' a single bitcoin. Really doesn't make sense burning out your pi trying to submit a single share or two/day
Very cool project insofar as helping to distribute the bitcoin network even further though. I'm kind of curious as to what their roadmap will be for supporting 20MB/block change if/when it ever comes into being.
You could run this setup with a 2TB USB External Hard Drive, the problem won't be block size but RAM to process UTXO (unconfirmed transactions)
Still I use a pi to run a few terahashes of mining equipment. It works well. The CPU doesn't hash but managers the miners fine.