Originally posted by jct us101 Have you also considered the DA 50-200mm? It's not as good in quality but I think it would beat your 20-200mm in quality. Just get the DA 18-55mm kit with it too, that's a great lens. That way you can also save a bit of money considering how much cheaper the DA 50-200mm is.
I would add that the DA50-200mm is lighted than the 50-300mm and this might be relevant to a light-weight camera like the K-x.
However, if you want the lightest load (eg for outdoor bushwalking), another option to consider is the DA18-250mm to replace both lenses (18-55 & 50-200/300): it would be lighter overall and no need to swap lenses.
Hope that the comment may assist...