I have a "Pluggable" 7-port hub (3.0A, 5.0V output) but am waiting on Erupters (2). I'll definitely post back with my results when all is up and running.
Hubs are INCREDIBLY important, 9 times out of 10 when I am helping someone out with an issue it is the hub at fault (the other time it is the SD card).
Be prepared to go through 2 or 3 hubs before you get one that works right and if at all possible don't run your pi off the hub that is running your miner.
Neil
My current setup is with 2 hubs, one powering 5 erupters and the other one powering one erupter one fan and the Rpi.