I use a print stylesheet in my wp theme to create a print-friendly layout of articles on my site.
I'd given the default style.css of my theme a media attribute of 'screen' to ensure no intereference with the print style sheet.
Thanks to some user feedback, I've discoverd that W3TC changes the 'screen' media attribute to 'all' upon minifying. This causes all sorts of printing problems which could easily be avoided.
Is there a setting to control css media type somewhere? I haven't found it yet.