Hello
Yep, you have a lot of research to do..there is a tremendous amount of information out there. You will be swimming before long.
Other than what has already been mentioned, and one of the strongest points in purchasing in my opinion....the M6 requires NO BATTERY. It is purely mechanical requiring battery only for the meter (which is not even necessary if you have experience.)
This is one of the mainstays and reasons for purchasing an M I feel. Being free of batteries is a dream. Period. (Especially in this digital world...)
Every time I have found my wife (pro photog) have to charge batteries or have problems as a result of needing to charge/change batteries, or when I must use her canon for whatever reason, my strong anti-battery sentiment always becomes so readily apparent again..and I am so thankful!!
The M7 works without batteries only at 125 I believe, otherwise battery operated.
I cannot stress how nice it is being completely free of batteries....
And if I havent mentioned, I hate batteries. Hate to have to worry about charging them, changing them, etc..
The M7 drain may be low, but it is nice being free from them nevertheless.
You are apparently novice, but when travelling in places where you can't change them, find replacements, lose replacements....sigh...it is a godsend.
Anything that takes your attention away from a project is a bad thing, and there are always so many other things to remember when travelling, working, etc.
Why waste energy worrying about batteries?
That's all I have to say about that...
best of luck
D
Say "NO" to batteries!! got it? good.........<laugh>