Having once held John's MZ-S, all I can say is that it is a very fine camera. Haven't held the PZ-1, but if money were no object I'd definitely get the MZ-S.
My .02 -- based on nothing much -- except some random fondling. ;-) Marnie aka Doe Well, except the fact that it's not an old camera, ergo, less likely to break down. That may not be a minor point, come to think of it.