Well, for those of you REALLY wanting to go back to the old baseband, the ONLY way you can do it is to flash the ~ESD56/2.0.1~ .sbf flash file. Period. End of story. NOPE, no other option. The location of the baseband in the phone's system is in a way lower area than any nandroid backup or restore will ever effect. I don't know if it's spelled out in the other posts about using the baseband update file(s), but it's in my guide about it. When updating to the new baseband, there is no reason whatsoever to make a nandroid backup, blah, blah blah, as I already said.
You probably already have the files, but if not look in my sig below.