I've frozen and later thawed/smoked spare ribs with no apparent loss in quality. Never froze any butts though but I wouldn't hesitate.
A couple years ago a local grocer had whole beef tenderloins for $4.99.lb. I bought one, sliced out the middle sections - think filet mignon - and roasted the other parts on the grill. They were fantastic! I went back and got another and stuck it in the freezer. When I thawed it and treated it the same way, it was a little tough. I don't know if I got a tougher piece of meat or if freezing toughened it. I think that for something like pork that gets cooked thoroughly, freezing is not a problem. I don't know if the same is true of something like beef that is often cooked rare.