The myth of using brass nuts (much the same as zero frets) was settled back in the 70's by an article in the late lamented "Frets" magazine which concluded that adding weight to the end of the neck increased a guitar's sustain. Stick a G clamp on and try it for yourself they suggested.

A guitar builder friend of mine, who has, in the past, built instruments for the likes of Gordon Giltrap, John Renbourne and someone called George Harrison, contends that brass bridge pins will increase the trebble response of a guitar. It's all down to mass. Shaving the bridge to lower the action, rather than a full neck reset, will reduce the mass of a bridge and the weight, and a guitar's tonal characteristics, can be restored by using heavier pins.

Stick 'em on a Taylor as Bublyrat has and it'll sound even worse!