I've got a GX-10 and remain delighted with it. I've not handled the K200D but think, of the three cameras you mention, the GX-10 would still be my choice. After all, it's pretty well identical to the K10D but cheaper. As regards the K200D, I've no use for scene modes but find having two control wheels on the GX-10 indispensable. Also, from a review at www.digitalcamerareview.com "Unlike the K10D from which it partially derives, the K200D keeps dedicated controls to a minimum, meaning adjustments to parameters like AF and metering modes must be made via the main menu." I know I'd find it annoying to have to delve into menus for such important and frequently changed items. Also, I enjoy the bright pentaprism viewfinder of the GX-10 and read that this has been downgraded to a pentamirror on the K200D.

Having said all that, if the GX-10 is going to cost significantly more than the K200D, I'd be less certain - especially as the K200D will, I assume, come with the Mk 2 version of the standard 18-55mm lens, which is meant to be an improvement over the original. Having said that, I find my standard lenses (I got the twin lens kit which, I think, offers amazing value) are very good and easily up to producing A3 prints.

Maybe you need to go to a shop to handle them both? Or, at least, the K200D vs. the K10D. I think that would help resolve your uncertainty.