Grade 5 separation here, on September 17 2015. Had surgery on October 1, 2015. Today is November 11, 2015.
I was going down a barely hikeable section of trail (~-40%) and got off line, front wheel hit a bush and I went out over the bars and down, driving my left shoulder into the trail. I instantly knew something was really wrong, the bump and inability to use my left arm made it pretty obvious. Had to hike out by myself with my bike and backpack, wasn't very fun!
The ortho said if I had surgery relatively quickly, my own ligaments would regrow with the cadaver ligaments (he did the anatomic reconstruction) and create a strong joint. He said that if you wait awhile, like a snowboarder wanting to finish the season, the joint won't heal as well because your own ligaments won't regrow once they're in their chronic state.
Now, 6 weeks post op, I'm in PT. Shoulder got pretty stiff after surgery and ortho got me into PT sooner than anticipated. I can almost passively raise my arm 90 degrees to the front, and every visit I get more range of motion back. Still in a sling, my ortho wants me in it for 3 months (end of December). Sleeping is easiest propped up on the couch - I can sleep in my bed but I'm up every hour or so to shift positions.
I've been hiking a lot to keep active. Both PT and ortho say I'll be back to 100% when this is all said and done. After surgery my shoulder looks totally normal - no more bump - and aside from the pain and immobility there's no more of that disconcerting "disconnected" feeling that I had after the injury but before surgery.
I'm glad I had the surgery. One buddy just had the same injury, treated by the same doc, and 4 months later he's riding at 100% again. Another buddy had grade 3 separations on both shoulders, and had one operated on and the other not. He says he wishes he had surgery on both because his non-op shoulder just isn't the same, pushups etc. are sketchy.