I have a droid 4 with ICS loaded on it. Is it safe to do a wipe data/factory reset on it?
When you say you are on ICS, are you talking about one of the ICS leaks? A factory reset shouldn't break your phone if that is what you are asking. All it really does is wipe out all your personal data.
A "Factory Reset" doesn't do anything but wipe user install apps and configured settings. As a "user" has no access to /system or anything else a "Factory Reset" does not touch those protected partitions. It has no clue or idea of what OS you are running, it just wipes out all the configurations you've done and the apps you've installed.
This is why a "Factory Reset" can be so bad for users who root their devices and do things in the /system partition. Some "bloatware" apps are needed for the setup process so when all that configuration information is wiped...and the apps are no longer there to run because a user deleted them....the setup process fails and the user is unable to complete a boot of the device.
There is no backup/spare/hidden copy of the OS on the phone. What is on it is what is on it.......stock, screwed up stock, updated to ICS, whatever.....Factory Reset doesn't do anything with that aspect of the device. It just wipes out your settings/configurations/data/downloaded apps.