Thanks everyone for your replies so far!
I take it the K-x is about the same size/weight as the DS?
I was tempted to upgrade to the K-x, but the smaller size of the Pen/GF1 is tempting for a 2nd body/travel camera.
I wonder how important is the IS, which is missing in the GF1? I suppose composing on the LCD away from the body would induce more camera shake? Otherwise, the GF1 does look superior from pure specs, although I've heard the ISO performance is not as good as a Pen.
But essentially, I'm just wondering how the Pen would compare to what I've got now, i.e. the *ist DS, on things like ISO performance, focus speed, shutter lag, size, weight, etc.
Thanks again!