Hi, Ira! It's great to hear from you again (missed you, and yes we are long-distance friends. Tell your wife that I absolutely LOVE her Amsterdam Bridge.
I don't notice much difference between the SR on the K10 and the K100,so I think she'd be happier with the K100 because of the size/weight issue. While I like the extra controls on the K10, the K100 is a joy to use and I still use itall the time as a second body or if I'm using manual lenses.Whenever I get frustrated with the K10 (and I do on occasion), I leave it at home and just play with the K100 -does the trick every time.
I know what you mean about sports cars, though I'll probably never manage to own one. The closest I've managed so far is a soft top Wrangler, which is also a blast to drive without ever leaving first gear (unless you happen to be in 4-low).