Well, as far as painful...It would be like wearing a cod piece for one of the Fetts.(Mine is Fiberglass). And to tell you the truth, I have not ran into any uncomfortableness while wearing it.
Kinda weird doing a fiberglass Vader cod. But, it doesn't look horrible. Better shape than alot of cods I've seen....
....Wow, that last part sounded bad :lol.