I generally only keep stocked trout on opening day - it's kind of a tradition. Also the way they stock the local streams there's no way all those trout are going to survive.
I generally release all other fish I catch, expecially the local wild trout. I will occasionally keep stockies in early summer, since I know they're probably not going to make it thorough the season anyway.
I guess if I were on a stream that I knew had a really healthy wild trout population, I would keep the occasional wild trout too. The streams that have wild trout in my area tend to have pretty weak populations, so I'd feel bad about taking one.
I really wouldn't judge someone who regularly keeps their limit of stocked trout though - they're stocked there so that people can catch them and eat them if they want to! Just as long as they're not wasteful.