I grew up on rollei's without meters, but after owning an m3 for a few months I really began to desire a M6 simply for the convenience of the meter and once I got one immediately developed a love hate relationship with the camera. The meter is terrible and the accuracy of the frame lines really leaves a lot to be desired. I much prefer to use an incident meter instead of craning my head all around with an m6 trying to decipher what it is seeing and then adjusting. I thought it would be faster shooting people, but its just not, not for me at least, ymmv. And no, there is nothing wrong with my m6...
I think the bottom line is really learning about metering. Years ago I thought TTL was the greatest thing ever until I started working around people who use meters professionally and watching them work and learning alot about lighting. Now that my standards for myself and my photography are a little different, using TTL metering when shooting people is a total drag because most TTL meters have too wide of an angle to be particularly useful as a spot meter for me. Its much faster to use a hand incident or spot meter depending upon the content that you are trying to shoot.
All that said, the meter in my CL is amazing. I wish M5's werent so big, Id get one just for the meter.
Not having TTL metering doesnt effect my style. It allows me to meter, then worry about the style of the shot. Having a camera stuck to my face while making lighting decisions is a total drag with the fiddly m6 meter, that sentiment times a million in a backlight situation. Most of my comments are geared towards shooting people in a documentary context where I want to have as little time as possible between putting the camera to my face and releasing the shutter for the first time. People not used to being photographed for a living tend to get antsy while they are looking at you not taking a picture of them because you are having a personal war with a 30 degree (or whatever it is) spot meter in an M6. So if anything, the m6 meter completely negatively imapcts my style and I get much different results with that camera than with a meterless camera. Sometimes its convenient without question, which is why I keep the camera, but for any serious portrait work I find myself MUCH better off with an M3 or an M4. Personal preference for sure, but there you go.