Luke, for what it’s worth, I think of dual-sport bikes as you do. Basically street legal dirt bikes (perhaps with a bit of a longer service interval…) Traditionally that’s been the focus of the club, not to say that folks don’t also ride other bikes.
I think the category “Adventure Bikes” is a media / manufacturer creation that is about much bigger and heavier bikes. If you believe BMW you need a GS1250 with aluminum panniers. The mid range bikes that Kurt mentioned definitely have there place, but those things are still pretty damn heavy, and take a lot of skill to ride off-road. No sane person chooses one of those to ride single track.