That really brings back memories. The early 70's were when I was most active, photographically. I graduated high school in 1970 and went right to work as an assistant to a fashion photographer here in LA. What a great job for a kid!
The summer after that I got a job as a sales clerk in the Beverly Hills Camera Shop, and I remember poring over the 3/4 inch-thick Leica full-line catalog. You're right: every imaginable accessory was available at that time. I had just started shooting 2 1/4 square (Hasselblad), so I didn't have extra money for a Leica. I finally found a good deal on a clean used M4-P around the end of the 70's.
I agree that working with an M and a separate handheld meter is a great way to develop photographic skill, and that's exactly what I did for years. It was great to get away from all the automated features in SLRs at the time: the Nikon F3 was technically a great camera, but I got lazy with it. The Leica and my trusty Gossen Luna-Six SBC got me back on track, and I found I enjoyed photography more.