I haven't used a R-pi - but my home setup has 2 "normal" powered hubs (2.0 Amp) with 4 block eruptors on each. Hum-ing away fro over 36 hours now. No problem.
Cool, thanks for sharing.
In case anyone else is interested, the hubs I'm using where I can get 5 or 6 usb block eruptors running with raspberry pi are these ones (d-link 7 port DUB-H7):
http://amzn.com/B00008VFAFIt'll do 6 without a fan, or 5 with a fan. Specifically, I'm using this fan:
http://amzn.com/B003XN24GY