As to good contemporary music at a parish function — I say let the horses loose. I go to Mass to heal from all the bruises and bumps I incur during the week and to thank the Good Lord for getting me through another one. I arrive early to pray before the presence of the Lord — not listen to rehearsal or tune-ups. That's the sign of amateurs. When the curtain goes up, you've prepared, you're ready. You don't have dress rehearsal when the audience is arriving. Bad form. That is just my very humble opinion.
I’m with you 100%. At the pot luck or parish carnival, play whatever you want. But the sanctity of the mass should be off limits to amateur arrangements and watering hole rejects.