Seems a little too flip for a house of God.
A web page from one of the stone carvers at the Cathedral:
http://www.stonecarver.com/cathedral.html.
Gargoyles had a purpose initially, they also were sometimes used to tell a story, much like stained glass windows in a medieval church. Now they are mostly decorative. I don’t have a problem with them, since gargoyles are consistent with how cathedrals have been built for hundreds of years. The cathedral is built to the glory of God, but it is for the people. If the people want Darth Vader, then why not have it there? Vader provides a meaningful image of evil in our time.
Those are the demons riding on your shoulder. They hop off and what for you while you’re inside. If you get right with God, those demons don’t get back on your shoulder as your leave church.