I used to shoot professionally with Nikon FM2's and FE2's (IOW's SLR's). Now I just want to shoot B&W for myself. I've always wanted to upgrade to Leica and am tempted to go with an M rangefinder. I'm hoping this change will spark some creativity. How hard is it making the change from TTL to rangefinder? Am I asking for trouble? Which camera model should I start with?