Well i think the first thing i would look at is the lyrics, a lot of them these days have out of context and misleading lyrics. And about the music, the gospel is reached by different group of people with varying tastes for music. If i lived in the time of david, maybe i wouldn't have liked the style of music.. But the words speak to me. And hmm, metal.. i listen to some.. the growling stuff, i don't know about that.. my friend performs in a gospel heavy metal band. When he performed for the first time, i thought it was far from anything gospel till i listened to the testimony at the end. So if gospel reaches to someone in a desired style of music, i believe its not a problem, just my opinion though. Thanks!