A couple of other things that might greatly influence the acceptance of a degree back in the US or other western countries are language of instruction and the field of study. I know a few non-Chinese China studies academics back in the US who did MAs and even PhDs in Taiwan in the 60s and 70s. All of them agreed that it was a bit of a gamble to have done a higher degree in Taiwan, but their qualifications were accepted once they went back to the states. The main reason was that even though the quality on the conceptual side of their degrees may not have been as good as a US degree, since the degree was in a China studies field and they had done the whole thing in Chinese, they were generally ahead of most folks of their generation who did their degrees in the US and only went to Taiwan or the mainland for language study.
I think this still holds true for anybody contemplating post-grad programs in both Taiwan and the mainland, but especially the latter. If your field is obviously something that is best studied in Taiwan or the mainland, then you could do quite well for yourself by doing a degree there. However, if you are studying something that has no strong link to the place where you are studying, then I see no benefit in doing it in Taiwan or the mainland. I know or know of folks from western countries who have done MAs and PhDs at mainland universities, especially Beijing Langauge and Cultural University. The ones who did degrees related to teaching Chinese had little trouble when they went back home. The ones who did degrees in straight linguistics pretty much wasted 3 or 4 years of their lives.
I would run, not walk, from any program taught in English in Taiwan, especially if you have any intentions of improving your Chinese langauge skills. Your classmates will be there to use their English, no matter how poor it might be. After having experienced a supposedly premier post-grad program taught at the University of Hong Kong in English (a place one might assume to be better suited than Taiwan for an English language program), my feeling is that most programs taught in English to Chinese students are to varying degrees dumbed down. Most serious students who are good enough to do a masters or PhD in English will do it overseas.
To sum up, I think doing any sort of humanities or social science degree with a China/Taiwan focus in country is a good idea provided that you’re keeping an eye on the way your field is going back in your home country. You’ll need to maintain or establish connections there if you intend to teach or work there after graduation. Doing a degree in a field that is not specifically China/Taiwan related (i.e. an MBA, Med, MA Linguistics or , sorry , MA IR) in my opinion is at best a gamble.