Love the XKSS, and of course the BMW motorcycle. Almost bought an R69S way back when, but got a Harley instead...should have gotten the BMW. Thanks for the incredible report FX, and as always, your photos are superb.
I really love the watch. Not only is it drop dead beautiful, but also very versitile; like the WG 1815 Chrono (esp. the original model) it can be worn anywhere with anything, especially if one changes from the black strap.
I really like the Sax-o-mat movement with the micro rotor. Of course my only Lange automatic, an Anniversary, has that movement, which might bias my opinion.
I also once owned the Anniversary, but in a weak moment, let it go, and almost immediately regreted it. Fortunately, not too long ago, basically by just being at the right place at the right time to take a phone call, I was able to replace it....
My experience was the same as yours. I owned a Pt Dato, but found it uncomfortable, let it go, and picked up the same watch that you have. I've never looked back.