No app backup for me. On 2.2, Google will automatically backup/restore your downloaded apps. The ones it misses are right there in the market
This is what I used to do - even in 2.1, right after flashing, I would go right to the market and reinstall all of my apps. That is a key point for 2.1, by the way - the first time that you go to the market after setting up your account on a factory reset phone or ROM, all of your apps, even the free ones, will be in the market. Once you leave the market, only your purchased apps will remain (though sometimes the free ones are there; you just can't count on them being there after leaving.)
However, Titanium is great because I don't have to go in to each app that requires a log-in and re-credential (an app like Evernote or a Twitter appor Facebook are examples.) I use randomly generated passwords for everything, so each of these requires starting Lastpass, search for the site, copy the password, start the app and log in.... it gets tedious. I figure that Titanium will save me those 15 to 30 minutes, so why not use it?
I should note that when I am restoring in Titanium I do not simply reinstall everything - I go through the list and decide which ones I am no longer using, deselect them, and then do the batch restore.
The process was fresh in my mind last night because I had just flashed Kaos Froyo V33 from scratch - then had to quickly nand restore back to V32 when I read about all of the problems people were having. I'm on to V34 later this morning, once that phone call I am expecting any half hour now is done.
And then I'm going on the Zach and Tenzo's Vanilla 2.0.3 (or whatever they are up to) for the weekend.