I had a grade 4 ac joint separation around this time last year, fully tore all the ligaments. I'm about a year out now and everything went well. The surgery aspect sucked for a while but it wasn't as bad as my knee surgery. I was able to go back and ride for the last day of the season and it's been fine ever since.
You'll definitely have to work at rehabing it either way, so be diligent about that.