Actually, I'm also a fan of heavy arrows. However, with the above senerio, he has a given arrow that has certain flight characteristics. He's somewhat limited as to what he can do, without weakening the spine too far. As long as he's going to use those light weight arrows, he should still tune them for the best flight, nothing else. Now, when it comes time to buy a new dozen, get some hunting weight arrows, stiff enough to put a nice heavy broadhead on and then he'll notice a real difference in penetration, without screwing up their flight.