My first couple SX-70 type cameras were acquired at the Santa Clara Camera Swap. Unfortunately they were both worthless. Crudded up mirror in one, dirty rollers in the other. I also bought two different, useless, flash accessories before I obtained these 680 SEs. I paid a premium for the 680s, but they were in mint condition. The meters are not all that accurate, but I've learned to adjust.
As for the 600 film, IMO it is not as fun to play with. It seems to harden faster and isn't very responsive to my scribbling in the first place. Regardless, I am sure there is someone out there who finds it aesthetically attractive in spite of these tendancies.