Drywall or OSB???

[JRH]

I have almost finished wiring a new detached garage that will be used primarily as a woodwork shop. I am undecided if I should do the ceiling in 7/16 OSB or 1/2 drywall. I am doing the walls in 7/16 OSB. I can do either one myself but am thinking in the possibility of damage from working in the shop. Putting the possibility of damage aside and thinking otherwise, which is the best choice? Which has the best R value? Is there anything else to be concerned about with the OSB? The ceiling has trusses on 24" centers. Would the OSB sag between trusses?
Please let me know your thoughts.
Thanks
JRH

[pushkins]

I always finish with drywall, to me there is no comparison between the two (OSB and drywall).
Drywall joints can be finished smooth and have a seamless finish. OSB tends to flake over time, typically it is not designed to remain exposed even on an internal application.
As you mention it is a workshop I'd be concerned about dust collection on the rough finish of OSB and the fire hazard associated with exposed wood in a garage situation.
At about the same cost/sheet and a little extra time in joint finishing drywall makes for a better finish.
You might also want to check your local building codes, many areas won't allow combustible materials to be use for sheeting inside a garage, I know you say your using it for a workshop but building departments/inspectors look at what the building "can or is" designed for. They are looking at future owners of the property who may not know.