I have the 7500 rev F with 5.02.00.07, just got it this year, haven't done firmware update.
I think if anything, Frontier pushes out the updates on the backend to the modems. I've never seen a firmware update page on their support website for the modems.
Same here, that is why I was surprised when it was downgraded to a previous release. I find it perplexing that they do not make the firmware available for download.