I've been a guitar player for the last 35 years or so, and started adding mandolin to the mix about ten years ago. The two instruments really do complement each other nicely, and I agree that the musical lessons learned on one can add dimension to the other.

I'm not a "chopper," however. The chop was developed in order to give a stronger rhythmic foundation to bluegrass, a music that is typically played on a bunch of stringed instruments with no drums or other percussion. In alt-country, there's usually a drummer, and hence less of a need for the mandolin chop. Admittedly, there are lots of guitar players in that genre who play mandolin as a second isntrument, and therefore approach it more like a guitar. But I also think that part of the reason you don't hear the chop so much in alt-country (or rock and roll, for that matter) is because it isn't really needed.