The K4 has a great dictionary but it's a pain to use. You have to keep clicking until you get to the right space. A touch screen would be much easier if you'll be using the dictionary a lot.
I've never had trouble with smudges on either my K4 or my NST. When I do clean them, it's to clear off dust, not smudges. They don't seem to have the problem that my iPad has with smudges at all. I wouldn't worry too much about that, personally.