I have both. I got my DX first. Then i ordered a K2 cause the DX is not "mobile" enough for me to carry aroung and read at the cafe or on the train.
Then i had to go back to my DX because my wife discovered the advantages of ebook reading
But if i leave the house i still try to grab the K2 or even get my old Cybook with me although i still have the DX. The DX is simply much to bulky for me on the road but i LOVE it sitting in my chair at home :-)