I have a choice: To get a brand new Leica MP body only or get a mint-condition M6 body only (previously owned but apparently unused). Which is the better buy? I'll leave the meaning of "better" vague. What is the essential differences between these cameras? The MP body will cost a lot more of course. (I already own an M7 but it is has now been sent in for diagnosis and repair of a peculiar problem with the film advance lever). Please give me your considered advice. Thanks.