That was interesting reading. I'll share.
1. The Yamaha China plant is owned by Yamaha and has been producing horns since 2000 (this also means that I'm late to the party
), so we have 16 years of time for folks to say that horns coming out of Yamaha China are junk. I didn't see any comments to this effect. Anywhere. Mind you, I didn't do the world's most thorough search, but when I search for Yamaha haters, I'm not immediately finding anything.
2. There appears to be some Yamaha stuff being made in Malaysia, which is immediately north of Indonesia, but they're two separate countries.
3. There are still Yamahas being assembled in the US using parts from Yamaha China, Malaysia, and Indonesia. Of course, that doesn't matter for the 40% or so of our members that live outside the US -- or, possibly, for the 60% that live in the US.
4. I saw at least one Yamaha dealer insisting that there are counterfeit Yamaha student horns out there. I didn't search terribly hard on that, but it's fairly easy spot counterfeit Yamaha pro horns: they cost about 1/5th what they're supposed to.
5. It's not very clear if Yamaha Japan is still making student/intermediate horns. Stephen Howard mentions that he was starting to see "Made in Indonesia" in 2007, but there appears to have been some cross-over then, still.
6. It's overly confirmed that Yamaha pro models are still made in Japan.
FWIW, all of the Yamaha horns I owned were produced prior to Yamaha Indonesia opening in 1998.
There was some comment that horns stamped "Made in Japan" are selling for more because people are starting to think that they're better than horns produced elsewhere, even though nobody's really proven that. I did see a couple folks trying to say that the brass is lower quality in China and/or Indonesia, but most of those folks get shot down with arguments like, "OK. Go buy a 475 stamped 'Made in Japan' and one stamped 'Made in Indonesia' and let's do some play tests. Oh, the Indonesian one is 5 years old and was flattened by a steamroller and the Japanese one is fresh off the line? Well, you need to get the Indonesian one completely overhauled to make a valid comparison."
Also, FWIW, when you have to order through the Yamaha parts catalog, you're not going to find four different part numbers for a YAS-275 body. You're not given the option of which country to buy the part from.
Bringing this all full-circle or TL;DR: I see nothing that really convinces me that Yamahas produced in countries other than Japan are of any less quality than the ones produced in Japan. It's also been between 9 and 18 years that they've been around and people are still recommending them.