Since the fontQuality settings were implemented on the Mac:
the default font styling has now changed (it's much lighter), see screenshots below.
For me, old is equivalent to setting SC_EFF_QUALITY_LCD_OPTIMIZED, while new is equivalent to SC_EFF_QUALITY_ANTIALIASED.
I think we'd want to leave the defaults as they were previously (i.e. by not touching the fontsettings). I've attached a patch that does this.