Wow, I have the EXACT same issue. Tree Style Tab is so incredibly valuable, I simply can't use a browser without it for any serious work.

Agreed. Tree-style tabs is just too dreamy. Though I do find myself bringing up Chrome for things like Wave, so I have Firefox up for day-to-day research/etc, and Chrome for quick things and high-JS web apps.

There's a few that are just as valuable - autopager, firegestures, swifttabs.