I know that Nokia Pure is the right font for N9, but just a curious thought after notice the font in the first preview of N950 is using Nokia Sans

So, is there anybody who already change their system fonts and willing to share a complete tutorial to change the whole system fonts? Plus some warning (if theres any) for the consequences.

Or maybe theres somebody who already has tried to build an app or setting to change the system font?

Many thanks

UPDATE:
Long story shorted, i use FontManager to change my N9's font, and it works.
But there's one problem, FontManager can't change font script that using FONT_FAMILY_LIGHT, i change some scripts with FONT_FAMILY light and the font change like it should be, the next problems is there are too many .css files that i have to change the script manually.

Is there any shortcut way, so i can change all FONT_FAMILY_LIGHT scripts in all .css files to FONT_FAMILY light in just one command?