Well, I just tried some of the BASF branded GBL. 1.25mls seems to have put me where 1.5-1.75mls of Chinese GBL would have, so that's a plus, but for me the biggest thing is the better taste and smell.
The chinese stuff is revolting, but this has a much weaker taste, and the lower dose means it's weaker too. Highly worthwhile investment IMO, thanks shambles. Also, thanks for the post about transit kings a few months ago. I really like them and didn't really even know about the genre before your suggestion!