Also, I'm not sure progressive anything on the web is a better experience for users. I have a reasonably fast connection everywhere I use the web and I find it a much worse experience when I load a website and see a really low-res version of images that suddenly changes to high res. Likewise, seeing all the text laid out in one font only to have it suddenly jump seconds later when it's done "progressively" downloading the font that's barely different from the standard one.
It seems like what would be more helpful is a way to understand the speed of the connection and choose what to send based on that, rather than assuming everyone has a bad connection. Or make it so your web site doesn't need a bunch of cruft like fonts that the user doesn't care about and just loads quickly regardless of connection speed.