I thought about firewalling the TiVo, but if it can't talk to the update server, then it won't be able to get guide data. Not useful.

Skipping commercials is definitely one of the key reasons I've stuck with TiVo for so long. If YouTube TV at least allows fast forwarding, then that's the bare minimum and would be usable. The modern commercial detection and skipping is obviously preferable. That said, we're clearly drifting away from recorded TV and towards streaming TV, so this is less important than it used to be.

I'm not sure whether I would benefit from reformatting or replacing the drive. Certainly, it's a feature that this model uses 3.5" drives, which means I could enormously expand the capacity, but that's not really necessary. I'd consider going with SSD instead, although it's unclear whether the continuous overwriting will wear them out too fast. Mostly the question here is whether I'm throwing good money after maintaining a bad machine.