I ride a 1986 610 every day for the last couple of years. I think Miyatas are under valued bikes. I love it, rides great. Check out this link:
http://www.miyatacatalogs.com/2007/1...alog-1986.html You will see that for many years. The specs on the 610 and 210 FRAMES are very close with different componenet lists. Both are from Miyatas touring series with triple butted chrome moly tubing. I would restore and/or upgrade a 210 in a heart beat. The 310 appears to be a more traditional mid level road bike not set up specifically as a tourer. I would love to own one but not the first choice for touring.