HTC EVO 4G :: Don't Wipe Before Flashing Rooted Stock 2.2

The following post refers to this particular rom:
HTC OTA Froyo 2.2, *FINAL*, build 3.36.651.6 (Rooted) Odexed - xda-developers

Before I make a blanket statement about not wiping your phone before installing, I should say that the following info is based on my personal experience.

I was coming from a rooted stock 2.1 ROM with netarchy's custom kernel. I flashed the 2.2 froyo rom + radio + wimax, rebooting between each flash. I did not wipe before flashing anything (more of an oversight rather than being intentional). When the phone booted fully, I had all of my apps, homescreen layouts, settings, etc. And no problems at all so far.

I suspect that moving from Sense rom to Sense rom also helped. Not sure what would happen if you are coming from a non-Sense ROM. But it would appear that this rooted stock 2.2 ROM, which is based on an OTA 2.2 upgrade, was designed to preserve your apps and settings. After all, who would want to accept an OTA update that forced them to reinstall/reconfigure everything?

I recommend that before you flash this 2.2 rom, do a nandroid backup, so you can always return to your current state. Then try to flash the 3 zip files without wiping first. If it works, then great. If it totally corrupts the OS, not a problem, since your bootloader and recovery are still intact. Just reboot the phone into recovery, wipe, then try again. If it still fails, then you can fall back on your nandroid backup.