Source: Flickr
Or, just compare it freely at the camerasize.com, for instance:-
Ricoh GR Vs Pentax K-01
So, we can see the big difference between the GR and the K-01, despite that both are having the same Sony sensor, in the same size of course! :-o
In fact, the K-01 is designed to be almost "gripless". So, clever Pentaxians are always much adaptive and like to DIY to tackle those original Pentax problems. See this:-
http://www.pentaxfans.net/thread-136325-1-1.html
(in Chinese)
Is it much better (to hold) now? Good job, man!