For me I consider this new wave to have at least three levels.......

1: The all in "dual sport adventure" with anything from a small bore 2-stroke/4-stroke that will get you down the road to another single track with very difficult trail. Not for everyone but the most experienced of off-road riders. Usually as you mentioned a 650 cc limit but anything over 450/500 4-stroke is a challenge even for experienced riders IMO.

2: The 500/650 cc dual sport class bikes that you can do much more dirt/gravel/graded and paved roads without the strain of not having enough power to cruise at highway speed (i,e., Interstate travel) and also be able to carry some baggage like extra weather gear or even light camping gear. Many single track trails are still possible but you don't want to tackle most of them alone for lack of help if you get stuck. Not fun by yourself DAMHIK.

3: The "Adventure Touring" which is what brought about bikes like the KTM 950/990/1190/1290 Adventure bikes and the BMW GS to name just a few of the dozens out there now. This is like the world touring class SUV/Range Rover that is IMO a great alternative to a full on road only touring bike as you can carry lots more baggage, gear and a passenger and go just about anywhere down to two track type trails or difficult off-road section as a #2 group adventure bike can on the upper end of their ability.....once again you need to have a friend on another bike with you.

You would be surprise at the ability of the big bore #3 group adventure bikes, especially the KTM R models with 21" front wheels and 18" rear wheel just like the smaller bore competition and dual sport bikes. Adventure Touring with fewer limits than most any type of motorcycle. A great blend of most all motorcycles now.