What did they never claim? They are claiming to deliver x GH/s at y Watts.
Nothing else is claimed by cablepair.

Both have a history of delivering FPGA-based products.

If you are trusting BFL, why don't you trust cablepair? I really don't see a reason why you shouldn't.
(If I had to choose, I would certainly not believe BFL because many people who *do* have experience in this field say their claims aren't realistic.)

Disclaimer: I never bought any products from BFL or cablepair.