Been reading this thread with interest. Don't have a lot to contribute since I am not a 22 single action revolver fan and as a result really don't know the dimensions other than the Bearcat is "smaller" than the Single Six. The Heritage 22's have little interest for me. I have considered buying one of the NAA mini revolvers more than a couple times however. Why? Just for the heck of it mostly...
Haven't heard of the Ruger Shopkeeper. That is definitely an interesting little SA.