- peri24 -
you are indeed right - trying the cameras out is the best way, however I live in a medium sized city and the amount of used MF gear even in the biggest shop is rather limited. Even in bigger cities it would be hard to find 3 or 4 645 SLRs in the same shop. So I am just doing my homework on internet ...
.. BTW - what did you choose at the end and why?