So I updated to daten v46 (i think, mid 2012), but I think the files I had were mid 2010, so actually newer than the car. It didn't seem to help, I still can't seem to touch the radio. That thread and others are, unfortunately, not very enlightening. Also unfortunate: even though it's now been left to sit and chill overnight, the radio doesn't seem to be picking up the newly added $664
Edit: Hmm. Although on second look, veloearl in that thread seems to have used $644. Even though both of our 328i E90s are US. Maybe I'll just swap the code out and see if it works after a while.
Edit: Just switched the VO from having $664 to $644. I guess I'll let the car sit and think about what it's done, maybe it'll change its tune in a few hours.