Except that you can't point your hashpower anywhere but ghash.io if you buy it off cex.io 

To everyone comparing USB miners to any other miner in terms of ROI, $/GH ratio, or whatever - stop. They will never yield more profit than if you had bought BTC with the money instead, and they will never offer the best $/GH ratio. Everyone knows this. You're not some kind of modern Aristotle for figuring it out as well. What USB miners offer is flexibility: unlike buying "cloud" hashing power you can mine whatever SHA-256 alt you like; unlike larger miners they don't cost multiple thousands of dollars and Watt-hours just to get started; and unlike straight up purchasing a given cryptocurrency you can buy them with a credit card or PayPal - none of this pfaffing around with exchanges.

If you consider yourself a "serious miner" and you've got hundreds or thousands of GH/s at your command, fantastic. I applaud your dedication and financial contribution to keeping the network secure. But don't you think that coming into merchant threads and moaning about how their products are too expensive for you is a bit beneath you? If you have the cash for a big miner, go spend 15k on 6TH/s from Spondoolies Tech and see how fast that ROIs (hint: it won't, not any more than any other miner will - including these).

Alright, rant over. Thanks for reading