Everybody knows what NPUD is, right? In this case, it's almost like an NGD, because my best acoustic, an SWS Maritime MJ, has been transformed. Recently I installed a Schatten HFN, a newer design that's been all the rage over at AGF. It's a piezo strip about one inch long that sits on a three-legged bridge structure, mounted on the back of the bridgeplate.
Although it's a piezo, something about the location and the internal bridge placement makes it sound very different from USTs. Without much experience with other aftermarket systems, I'll just say that I love it. Very realistic sounding, and crispy on top. Sounds more like strings than electrical signals. I'm reading about folks removing their K&Ks in favor of this.
It's an active model, with battery bag and tone/volume controls. Nothing is visible except for the black control dials, which are visible for abut 1/4 inch at the edge of the soundhole. The top braces are close to the soundhole, so the control board can't be mounted further back. Anyone with a similar model Seagull who's concerned about this might want to select the passive model.