We introduced some organs once the dogs were doing quarters for a while, but we haven't had to buy organs separately anymore. The quarters and backs that we get still have some attached, so they get a little bit every day.
We've been adding beef heart to meals lately, to get winter weight on (one more ADBA show next week though) and most do fine with it. Kane can't handle a whole bunch every day, but otherwise he's fine with it. I'd love to get my hands on venison and other meats to start feeding!