I had a grade III acromio-clavicular separation several years ago. The orthopedic surgeon I saw said the outcomes would be pretty much the same with or without surgery, so I opted against surgery and got a couple months of physical therapy instead. Several years out, I can tell the affected shoulder is not the same as the other, but I have full function, range of motion, strength, etc. If I had the opportunity to do it over, I don't think I'd choose differently.