See:-
http://www.dxomark.com/index.php/News/DxOMark-news/The-Pentax-K-01-the-second-best-hybrid-sensor
So, theoretically K-01 is close to the K-5 in IQ but still it is not there. Nonetheless , I just wonder if one would see any practical difference in real world for what are measured. On the other hand, some other different characteristics may be easier to be spotted by the users, e.g., the different colour rendition and tendency.