My first experience with the Shimano 600 group was just a handful of years ago when I was gifted a Trek 600 bike that was too small for me. I completely went through the bike as it had been sitting for many years after the original owner was involved in a serious car accident just weeks after buying his bike. He never got to ride it. It was very near NOS. I had to test ride it so I put a long seat post on it and took it for ride . The 600 group was pretty amazing and the shifting was accurate and smooth , the brakes were very effective and I particularly liked the feel of the brake levers. I am , by my history , a Campy guy and go for bikes about a decade earlier than the Trek but I have to say ,that Shimano 600 stuff is top notch. I am now building a mid to late eighties Medici and am putting Shimano 600 brakes on it , they stop so much better than other side pull brakes. Oh , and I ended up giving the Trek to my son in law for him to enjoy.