Also, as far as WikiFont-Glyphs goes, the support goes back to IE8, but I have a patch (if needed) that can extend this to IE6 with HTC behaviors.
IE8 support works fine for us. Sam's SVG patch doesn't actually have 6 or 7 support, it just falls back to no icon with normal button appearance.
If this is the case, the only blocker for us to convert to it would be creating a WikiFont icon for suggestions (we're currently using a lightbulb in GettingStarted), which is an easy design task on our end. I'll make sure Sam, Matt, and Rob take a look at your patch and we come to a decision about it all.