I'm about 1-1/2 hrs East of you with a 640 Adv that you can test-ride whenever you like.
I've only had it about 2 months, but I'm really enamored with it already. I got it because I wanted something dirt-worthy that I could ride to the dirt. It's quite a bit better on dirt than I expected, given the weight, and waaay better on the street than I thought it would be. If I had to give up one of my bikes right now, it would be the Beemer.
But, when it comes down to it, if the wind protection and fuel capacity of the Adv don't matter, the LC4-E and SXC will serve you just as well, if not better. It's a great motor in a great chassis. You just have to decide which bolt-ons are most important.
Problems cannot be solved at the same level of awareness that created them.