Vaadin 6 and Font Awesome compatiability issues

I was wondering if there are any known issues with using Vaadin along with Font Awesome for Vaadin 6.x?

http://fortawesome.github.io/Font-Awesome/

It seems like cool technology but I’m a little leery of using a library that depends on very sophisticated CSS given that IE 9 doesn’t even handle drawing buttons with gradients and rounded corners properly even using their proprietary CSS.

I am aware of the Vaadin 7 only plugin which uses Font Awesome and it appears to have issues with light testing:

https://vaadin.com/directory#addon/fonticon

For example the demo link is very slow (http://marc.virtuallypreinstalled.com/FontIcon/) and with Firefox 22 is experiencing rendering issues as described here:

http://superuser.com/questions/446001/firefox-cannot-render-icons-from-font-awesome-webfont-set

And this doesn’t look too good either

https://www.google.com/search?q=font+awesome+not+working&oq=font+awesome

But other non-Vaadin sites have reported success using it.

My main question is there any danger of Vaadin and this library running into compatibility issues given it’s relative complexity?

Thanks