Here's my experience unrooting my Razr.
I had to unroot to return my Razr for an exchange. Tried Z4 and although it said successful, when I looked in the app drawer, Superuser was still there and all root apps still worked. I then tried Doomlord's unroot at XDA and got the same result. I thought maybe Z4 might have removed something from the original root script, not letting Doomlord work, so I ran the root again (successfully) and tried Doomlord's unroot again and it worked. Did a factory data reset and boxed it up to return.
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