I had a Heeler/Border Collie mix when I was growing up (have I mentioned this yet?) and she was great. We had a fair amount of problem behaviours with her (think two young children plus she didn't join the family until she was 8 months old ... plenty of bad habits already formed since that's why her last owners dumped her at a friend's farm), but to date she was one of the most awesome dogs I have ever owned (even if you include the current guys). I wouldn't hesitate to bring an ACD home and I don't think I'd have to argue the case with anyone I live with.
I thought I'd bring everyone's attention to Jack A Roo. Jack is 1 year old and he is deaf. Despite that, he looks like a real go-getter and apparantly has some incredible focus.
Jack A Roo is currently in the care of Border Collie Rescue Ontario . You can check out their website or their blog for more details about Jack A Roo.http://www.petfinder.com/petnote/displaypet.cgi?petid=13329013