Hi Byteme,

Most USB hubs aren't designed for a lot of maximum load devices (which block erupters are). If you think about average computer users, they are more likely to have lower load devices plugged in - mice, keyboards, flash drives and so on, which aren't drawing anywhere near the 2.5W limit. So hub manufacturers design for a lot less than 2.5W per port.

Also, in general, yes it's probably fine to supply more power to a hub, and then run more devices from it. That said, with the current bitcoin mining difficulty, a block erruptor is not earning a lot, and you are almost certain to spend more on a power supply than you will ever earn back...