The USB flash drive type miner is very limited in terms of current (power) if it have to be USB 2.0 compatible
But these days, who says its current rating has to be USB 2.0 compatible? That has been extended so now only the link speed for 2.0 is relevant.
Forget thee not that the power needs of tablets, GPS devices, and smartphone has blown away having only 500ma available. Many now need at least 1.2A or more to properly charge and even more to be used while charging. Given that stickminers fall nicely into that extended power-hungry group, strict USB 2.0 compat is a non-issue.