1. I was able to restore all of my most important apps via Titanium, but not through batch, only one at a time. I ended up restoring 50 just to test it out. Not a single FC, issue, or hiccup.
2. I restored app data on several (where I really wanted it, basically Mint, Bar Tender, Facebook, Dropbox, Sugarsync, Sorami, etc.) again without any issues.
3. I don't use MyBackup, but I was able to restore my system backup from MIUI 1.3.18 FroYo without any issues.
4. Absolutely critical to do a full wipe with the works (CLEAR_TEMP, FORMAT_ALL, recovery wipe everything, etc.)
5. CM Camera works (front and rear), MIUI Camera no FFC, video works on both, and FB sync with contacts works for me.
Everything that this ROM offers is working perfectly for me (Swype, GPS, SMS, VVM, Wireless Tether, Theme Manager, MIUI Weather, MIUI ROM Downloader). I have only one complaint, battery life blows. I came from savage 1.6 so I doubt I knew I would have to get used to less battery life. Hopefully someone will develop a kernel that matches the 1.6 (on my phone).
I really believe the key for my success was in absolute OCD inspired wiping, flashing and then LEAVING THE PHONE ALONE for a hour or so.
After that, I played around with it and did minor setup, installed a few critical apps (Titanium, ROM Manager, Terminal and VVM) and then just let it settle in. I rebooted a couple of times during that period.
Then I slowly introduced some restored apps from Titanium, downloaded and flashed a theme and did a nandroid. Once I had around 20 apps restored, I restored my MIUI System Backup, did another nandroid and finished setting everything up (all accounts, settings, apps, DTa2sd, etc.) No persistent issues whatsoever. Had to do a GPS fix (## menu on sense) and had to reinstall Swype (took about 30 seconds) and that is about it as far as "fixing" anything.
If anyone has any doubts, I can share screens of everything working. I don't feel like I will have to complete this process everytime I flash a new release, but I do believe it is critical for success coming from FroYo to GB.
My advice, don't mess around with 1.3.18 anymore, just wait for tomorrow's release and then do what I did (above) and I am confident you will have a flawless (near flawless for some, bug ridden for the lazy LOL) running MIUI v1.3.25!!