Here is a 1993 Yamaha C6 (6’11”) in like-new condition. One owner, S.F. Bay Area.
It has a big, sonorous, concert sound. Some performers prefer it to the slightly longer C7. It has a different stringing scale with better resonant, singing tone in the upper treble.
By the way, for a comparison, we also have a 1989 Schimmel model 210 for sale.