I have the Barley Crusher also and have had mostly good luck with it. I haven't had any issues with wondering gap but it does jam now and then. Pushing a small wooded dowel through the grain and giving the free roller a nudge gets it going. I motorized it 4 years ago and really like the ease of use now.
It is due for a cleaning though because as the bushings wear dust can get in and gum things up. I haven't kept track of exactly how much grain has gone through it but it's at least 1000lbs.
My only complaint is that I should have gotten the larger hopper. I have the standard small hopper and it only holds 7 - 8 lbs at a time. The problem is I was cheap not that there anything wrong with the hopper.
Whenever this conversation comes up it is worth mentioning that everyone, generally, likes the mill they have. For a brewer who makes less than 100gal per year, like me, the BC works great. If you plan to brew up to the 200gal limit you may want to consider a MM for the more industrial build.