Denis, I am in a similar position as you, although I do not own a M6 (yet?)!
Currently I am using a Bessa R3A that, off course, have an internal meter but also "manual mode". A few weeks ago I bought a Seconic 308 incident meter, and I only shoot manual since then. I have now learned pretty good to make exposures without the meter, at least outside on a good day. I also sometimes, which stresses my girlfriend, carry the meter around just to excercise!
I really enjoy manual mode, and the incident meter have tought me that it is much, much, easier to estimate exposure than I thought. The reflective meter in the camera changes quickly with colors in the motive, which earlier made me think light metering was SOO difficult and complex.
Anyway, I am for some time now looking for a M4,M2, but thought M6 could be a good, newer, alternative. But only as long as the meter reading can be turned off. I dont like the R3A's desparate blinking to try to correct my artistic freedom to exposure 😉 , and want my next rangefinder to be without this.
jaapv, is it true? Can the M6 run all shutter times without the battery?
Anders