For what it's worth, I just thoroughly checked over my collectable minifigs and compared them to standard ones, and the difference is almost negligible. I'm usually pretty OCD about such things, but the quality isn't really all that much different.
I can post pictures if you want, but from the only real noticeable differences are the lack of an indicator mark on the neck, the different production codes inside the legs, and an overall lesser amount of sheen. I looked at them with a bright light focused on them, but I could not pick out any Chinese figures that began to look translucent. The inside of the feet do lack a copyright stamp, however, said stamp only appears to be in newer standard minifigs. I checked a few figures I had on hand from the late 80's to mid 2000's, and they were also missing the copyright info, it only seems to be present in non-Chinese minifigs made in the last few years.
All in all, there is some noticeable difference, but I honestly wouldn't let it stop you from getting one of these if you really like it.