I finally mounted the Shinko Tourmaster 230 tire on Saturday, and have ridden 200 miles, 1/2 of it 2-up. Here's my thoughts versus the ME-880 I removed:
1. From memory, the Shinko has one fewer ply than the ME-880, and seems to ride a little softer since the carcass isn't as rigid.
2. The Shinko is lighter than the Metz and is perfectly round with no molding mismatch
3. Shinko was slightly easier to mount and seat than the Metz.
4. Shinko required ~2 ounces to balance, the Metz required ~1.5. There is no observable vibration. This was a bit disappointing, but the tire rides fine.
5. RPM dropped 3% with the Shinko vs. the worn-out Metz.
6. At 41 psi (the max on the sidewall), the Shinko was harsh, but feels OK at38psi
7. Of course the bike handles better and is more responsive-- it has a new tire on it with a round cross-section-- I'm not sure I could fairly compare the handling or ride since the Metz was totally worn out, but I can say that the Shinko rear does well with grooved, cement pavement. The bike doesn't wallow as much on higher speed corners, but how much of this is simply because the tire is new, I can't say.
8. I got almost 20,000 miles out of the Metz, we'll see how the Shinko does...
Overall, a thumbs up so far. I'll mount the front in a week or two.