The only thing you can do is take him around with demo material of his choice and let him compare systems. Nothing to lose except time. At least he'll try new things. One thing you'll find out is how rare stores place Bose systems where you can "side by side" compare them to others.
Hey, when it really comes down to it, you're not the one who has to be happy with it! Their choice, their money! All you can do is offer help and advice if they're willing to take either.
Oh, and by the way, what I always used to hear in the business,
"Bose: where you get no highs and no lows!"
