Absolutely the yeast-forward Beam signature seems ideal for the Manhattan. Ditto many rye whiskeys which on their own are a little tough to drink neat (for many anyway).

I would advise for the neophyte Manhattan drinker not to use too much vermouth, 3:1 whiskey to vermouth might be good although I make it sweeter. But some will never take to it, fair enough.

Gary

P.S. Might I add that bitters are essential to the drink, it tastes "right" with them and incomplete without them.