I have bought and received one Atnminer S1. Looked fine. One blade died within 24 hours. It is on the way back. They promise a coupon for discount on next purchase.

Interesting enough, the bad blade was mounted with 5 torx screws, and one Philips screw. So it looks like the bad blade was not mounted at the main production line.

But I still have a good feeling about BitmainTech, and ordered another, and seriously considers the S2