Oops. Landing page font is almost unreadable in Chrome Version 30.0.1599.101 (Windows XP)
http://i.imgur.com/i5GwqIN.png?1
"Variablcs"?
A lot of thin fonts look bad in Windows especially chrome. So you could probably make a safe bet that if a font is thin on OSX then it will be much thinner (sometimes unreadable) on Windows.
If you want to use thin fonts only use them for the titles (but even here it looks like that causes problems).