Yup...too much risk buying a "proprietary" design from a defunct business.  For all anyone knows, they could sell it to multiple parties without any regulation (unless there are actually patents and lawyers involved, though again, HF's balance sheet would indicate otherwise).

On a side note...it would appear as though someone is testing/sprint burning ~30 PH/s at odd intervals to directly impact (or even directly aim to set) the difficulty, and perhaps the fiat price.  There's no way those two enormous booms in hashrate centered around the 1st of November and now December have been due to aggregate luck alone.