Tony @ EverydayCommentary put out an article last year attempting to standardize at least his own working set of definitions. This is his definition of "midtech":
"This is like my GMT Stubby Razel or the Tolk--it is a knife where the majority of parts and processes are done by someone other than the knifemaker, but the final steps--lock fitting, grind, and the like, are done by the knifemaker. There is a spectrum in handmade knives and at some point, let's say 50.1% to be arbitrarily specific, that the knife ceases to be a handmade object and more of a production piece. So long as the knifemaker still lays hands on each blade in a meaningful way, more than say, assembling finished parts, its a midtech; if not, it is a production piece."
Article here:
http://www.everydaycommentary.com/2015/05/taxonomy-and-terminology-change.html
I think that the definition is pretty accurate, especially compared to "production". The Nirvana is, to me, clearly a production piece, because Peter Rassenti doesn't have any hands-on role in the manufacture of these knives. If Spyderco were producing the parts, but Peter R. was assembling them, fitting the lock, and grinding the blade, that would be a midtech, and likely be significantly more expensive. The price on this knife as it is now is paying for materials(Ti, S90V) and machining(integral handle, exterior machined pattern). If I could afford it, I'd buy it, and honestly I'd rather have this than many customs because I think the Taichung plant has a better average F&F than custom makers(this is an EXTREMELY general statement; some of them are near-perfect every time but some are more inconsistent).
As for US vs. Taiwan, I think it's the height of pointless jingoism to (try to) exclude foreign-made products from your purchases. It's your right, but you're missing out. I just don't get the mentality that I'd buy a product of lesser quality just because it's made in a certain place. Plus, you literally cannot not buy something that's not at least partially sourced from other countries. Even if you buy, say, a Ford made in Michigan, it almost certainly has parts made outside the US. The Taichung facility is widely regarded to be at the very pinnacle of production knife manufacturing, and there's no way I'm not buying from there just because it's not "Made in the USA". Taiwan doesn't really have a steel-making industry like the US or Japan(or China, considering the progress they've been making), so when I buy a Taichung knife it almost certainly will have a US-made steel, and could very well have US-made materials elsewhere. Plus, that keeps the US-based Spyderco open for business, and enables them to make knives in the US at reasonable prices. I want a PM2 because it's a great knife, not because it's made in Golden(although that's certainly not a bad thing). I also want a Mantra 1, and I am totally ok with it being made in Taiwan and with US-made steel. I don't see the problem anywhere in that.