I have smoked several costco boneless shoulders...In fact, I smoked three of them for a July 4 party for over 100 people who thought it was the best BBQ pork they had ever had. In my opinion, none of it overcooked or dried out. I cooked it to 165, double foiled it, took it to 200, and it was just as moist and juicy as any bone-in.
That being said, bone-in shoulder is definitely going to have that added flavor that only the bone can provide. It's subtle, but it's definitely there.
Either way, you can't go wrong. The bone is good, but the THIN BLUE SMOKE is what makes it special. NEVER forget that.