Correct. However, the key is that the unbranded firmware HAS to be a HIGHER firmware than the branded.
This is the problem with the E62, and why you can't unbrand it anymore. The previous fix took advantage of a feature (that's no longer there) in NSU that allowed you to re-apply firmware. In other words, say you have firmware 4.00.01, you could change product code from Cingular to Generic and tell NSU to "re-apply" the 4.00.01 firmware. However, now, you can only apply NEWER firmware, i.e. 4.00.02 or greater. If they don't come out with new firmware, or if the unbranded is older than the branded, you're screwed.