To suppress extension checking, go into about:config, right click anywhere in the main menu, and add a new preference named "extensions.checkCompatibility" with a value of false. That way you don't have to patch the extensions one by one.

Not saying that they'll all actually work.

The link to cmSiteNavigation Toolbar site seems to be broken. Here's a fixed one: cmSiteNavigation Toolbar.

Okay, so does it fix the rendering bug where Firefox treats XML's empty-element syntax as a start tag?

I don't even want to TELL YOU how much XSLT I had to emit last week to keep that bug from foully murdering a new layout for a Cocoon-based application.

From a quick look at Tab Mix Plus, it seems that the main things it does, at least undo closed tags and session management, is included in Firefox 3.0 anyway, so maybe that extension isn't as important now as it was?

The features of Tab Mix Plus that I care about most are the ability to have multiple rows of tabs and the ability to move the "close" tab button off to a single button on the right hand side.

The cmSiteNavigation Toolbar bug seems to be fixed.

I wish someone would pick up the maintenance of cmSiteNavigation. I've found Link Widgets, which kind of replaces it, but it's just not the same.

It's on my list, but it's a long list.