I would say that what will be important in the future is power consumtion / GH/S ratio which should be better on the 20 nm chips than the 28 nm chips.

From the models you linked there is only Blackarrow that is 20 nm, the others are 28. Look also at KncMiner Neptune.

Smells a lot like fake.
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First post in the blog is 9 days old...?!

I would not buy anything...