I'd recommend against updating S9v1 units to the autofrequency firmware as it seems to increase hardware failure.
Even Bitmain now states the following:
* Attention: do not use this fw on old S9 miners with fixed frequency.
and have put up older fixed frequency firmware - which I'm pretty sure is still v1 on the bmminer.
There's a distinct chance that the posting of that by Bitmain has more to do with dealing with people (and their inexperience issues) than issues with actual rigs.