I am one of the only people I know who has a barley crusher and is not thrilled about it. Using the LHBS mill I was in the high 70's efficiency wise and after getting the BC I am down to around 73%. I am going to adjust the gap and see where I get, but so far that was a dissapointment. I expected to go up. Also, I had a weird problem last Saturday where it kept messing up. I was grinding and grinding and then something would happen. It was like a gear would come loose or something. The handle would turn but there was no resistance, so I dont think the rollers were turning. I never found out because after I dumped the grain out it was working fine again. This happened probably 20 times on Saturday, it was a very frustrating experience.
However, I have to imagine that I am just unlucky. So many people have used it successfully that I would imagine that more times than not it is a very good product.
FWIW, the best mill I personally have ever used is the Schmidling.