I purchased a used Atrix 4g off ebay recently, and after researching about unlocked boot loaders, rooting and the different versions it all seems like its based off your build number and seems more confusing than the other phones I've messed with. So, I want to do it right. I am on 4.5.141 like this thread states, but I am not sure if I have an unlocked boot loader. Is there a way to find out whether or not it is unlocked? The phone is not rooted. I tested with Titanium. What process do I use to unlock the boot loader? I have a stock 2.3.6 ATT build so I am unsure if I can use the RSDlite method used on xda for 2.3.4 without causing problems. That thread is kind of confusing.
Edit: I rooted using the above method and seems to work rather safely and easily for .141. Now on to trying to figure out this boot loader and ROMing.
Just wanted to mention that an App called Voodoo OTA RootKeeper works like a charm. My Atrix was rooted, and I installed this app. Ran it, it requested Super User Permission, then you can make a backup of your SU. After the update, you run the app again and restore your SU from backup.