i keep reading about putting a "Custom neck model" in the bridge, and was wondering how much of a difference the sound of the Custom bridge and the Custom Neck (in the bridge).
The Custom is supposed to give you more of a "dirty" and raw sound compared to the other Ducan P-90s. I know PRS uses a Vintage in the neck and a Custom-neck in the bridge. Apparently it goes better with the Vintage. So yes, probably less output, and of a less raw sound.