Is the delay in shipping mining equipment on purpose? Couldnt the manufacturer mine with the new hardware and deliver it in a few month, as said to be a production problem, but mining itself until the difficult level is too high, all on purpose, and then getting rid of the hardware? Its perfect, altough morally really weak, to mine with the equipment others pay for.
There are reports online that Butterfly Labs and Avalon were both doing this as some customers have received dusty equipment with mining pool information set, however it is just as likely that the equipment was shipped out with preset pools and customers plugged them in and didn't reconfigure settings.
https://bitcointalk.org/index.php?topic=236348.0 is an interesting read, however it all appears to be circumstantial evidence at best.
I bought a couple of Butterfly labs a 25GH/s and a 7.5GH/s in april. I got them in november, when complexity was too high already. So I sold them. I'm using cexio now. It is more expensive in terms of cost per GH/s but it is more flexible. And you get access to one of the best private mining pool, GHash.io.