I was on .214, rooted (D'oh), with a bunch of stuff frozen (nothing deleted).
I:
- Made a note of what I had frozen,
- unfroze it all.
- Installed Voodoo Root Keeper, backed up root, temp unrooted
- Downloaded and flashed the downgrade leak (
6.16.214 Downgrade Leak (To 6.16.211) - DroidRzr.com) to get back to .211 (you have to do this for the .215 to install) and let the phone "optimize" all the apps and finish the reboot.
- Back into recovery, wipe cache and flash the .215 leak (
6.16.215 Ics Update Leak (Install From 211) - DroidRzr.com) and let it finish it's thing
- Back into recovery to wipe the cache once more
- Reboot and recovered root using Voodoo Root Keeper
- Using my list, used the ICS "Disable" feature on those for which it will work (this keeps the OTA updates from happening - haven't figured out how to get TB to stop those) and then TB to freeze those things I want frozen which ICS won't allow one to disable.
Done! Total time - about 45 minutes.
Subjectively, it seems the phone is snappier, apps load faster, 4G connects more quickly (but just by a little). Looking at signal strength numbers (not bars) it appears 4G is about the same (at least at home). As for data drops - there's only one place I frequent where data drops happen and I haven't been there since the .215 flash. 4G speed is at least as good as before, maybe better. I just downloaded the ICS Getting Started Guide (PDF, 8MB) and the ICS User's Manual (PDF, 10.4MB) and I don't think it took 30 seconds for both.
Battery Life: Too soon to tell. I'll know more tomorrow. But, the phone runs much cooler than with .211 and, cooler than with .214 as well.
As has been noted before, this will take you off the OTA path, but it's also been shown that Matt's Utility (ver. 1.81, not 1.8!) will get one back to stock .211. When it comes time, I'll be trying the downgrade flash and see if that'll get me back to .211 without loosing all my apps/data.