* Recording in web client of Duolingo does not work on Firefox, only in chrome. * Webserial for flashing esp for example is not supported * Webauth took forever to be supported (still not sure it's fully supported)

But I still use of because of the cookie Mgmt mainly, and secondly because we need at least one alternative browser engine on desktop... Safari WebKit is a fork (or the original if you prefer), it's not really that different.