I like them longer, myself. Long enough to where if the arow falls off the rest, the head CAN'T touch my fingers.

One of my friend's hunting buddies almost sliced his finger off one time with a setup like yours.
His hands were cold enough that when he drew back, he didn't notice the arrow had slipped off the rest and one of the blades was sitting on his glove just as he released. This resulted in a very unpleasant surprise and a trip to the E.R.
Makes me cringe whenever I think about it.