It was the interim step between GPU's and ASICS. They actually pretty much set in stone the logical configuration of the gazillions of gates used in all ASCIC's for hashing SHA256. That *IS* after all, what FPGA's are mainly designed to do - be test beds for logic circuits to later be implemented in ASIC's.

And no, even today they cannot compete in speed or efficiency even when compared with even 1st generations of ASIC's.