I've never owned one, but a couple of past riding acquaintances had them. As far as utilitarian two-wheeled transportation goes, they're hard to beat. Certainly not a dirt bike, but a bike that can handle all roads.
Doohicky is a must-mod, and cheap (like everything on the klr).
Lowering is possible, like you mentioned. I see seats for the klr cut down super low so I suspect there are inches to be had just there.
I believe you will be better served by the klr over the CSC, hands down. The klr may not be "modern", but then again neither are our Ninja 250s. My first gen and the klr are both '80s tech and prime examples of Kawasaki's "if it ain't broke" mentality.
I hope the trade goes well and you have pics of the new bike to share soon, I suspect it will be a very good bike for your purposes