When I went from stock to Superclean 2.4 I had to wipe and did just that. I followed the steps to root phone, installed titanium backup, backed up everything to the SD with tibu, then used Odin to push 2.4 but in your case push the Superclean 2.8 that wipes phone (the first one listed), reboot phone and use tibu to restore apps and data but don't restore any system stuff.
From the Titanium Backup Wiki (yes it can be this simple):
How to make your first backup:
Verify that Titanium Backup has started without warning and that your busybox is OK
Click the Backup/Restore tab
Click Menu (the button), Batch
Click "Backup all user apps"
Let it run, then go back
Individually backup the system data you want. That is most green-colored items. This will be bookmarks, call log, calendar, launcher, WiFi, etc.
Now your backups are in the "TitaniumBackup" directory on your SD card.
How to restore your backups on a new phone, or after installing a ROM (if you wiped your phone):
Download Titanium Backup from Market
Click the Backup/Restore tab
Click Menu (the button), Batch
Click "Restore all missing apps + system data"
Reboot your phone
It's done ! The only thing you may have to adjust is usually your wallpaper/widgets.
TB - HOWTOs : Titanium Backup - Wiki
TiBU has a lot of options. It's really worth 10-15 minutes to read the other articles in the Wiki. It makes a lot of things clearer and explains some of the settings.