if this helps "a little bit", would upgrading either/both the tivo bridge and gateway to moca 2.0 help anything, or would I also need to upgrade the minis? And I'm guessing it would only help Tivo itself, and not our internet/wifi, but not sure?
Yeah, I realized after posting that I hadn't answered that question directly, but figured I'd let it slide in case it wasn't noticed.
But to answer... your modem sync issue is likely
just a matter of insufficient cable signal reaching the modem, not directly related to MoCA (i.e. perhaps the current layout of your coax plant to support MoCA connectivity, but not due to the MoCA signals, themselves); upgrading to a later MoCA spec wouldn't change that.
Even if the modem performance were due to interference from MoCA, simply upgrading the MoCA gear wouldn't resolve the issue; you'd be looking at the options posted in the linked thread associated with DOCSIS 3.1 and MoCA interference. That said, you have a gateway with built-in MoCA bridging, so MoCA interference wouldn't be the problem, unless the modem is actually malfunctioning. (Interference is a problem with some pre-MoCA and DOCSIS 3.1 modems/gateways.)
As for any benefits from upgrading your MoCA gear... If/when you ponder a MoCA upgrade to improve your LAN speeds, it would have zero benefit for your current TiVo gear ..: with the older Mini's (A92/A93) limited to MoCA 1.1 or Fast Ethernet, and the Roamio OTA limited by its Fast Ethernet port. From a value standpoint, any such upgrade would need to be for the benefit of other hardware that could use a wired network connection (e.g. streaming boxes, gaming consoles, PCs, wireless access points or mesh satellites, etc.).
p.s. FYI/e.g. ... The TiVo Bridge is standard MoCA 2.0 (up to 400 Mbps), but its current connections to other MoCA nodes on your LAN would all be at just MoCA 1.1 (up to 170 Mbps), since the link between any two MoCA nodes is limited by the highest spec supported by *both* nodes. Upgrading your gateway to a model that supports MoCA 2.0 or better would bump the throughput between the TiVo Bridge and gateway up to 400 Mbps, but the Roamio OTA still couldn't be faster than the 100 Mbps of its Fast Ethernet port. If you used a Gigabit switch at the TiVo Bridge to connect multiple devices, a device such as a gaming console might benefit from the improved throughput; and some leverage MoCA to improve the backhaul throughput between wireless access points or mesh satellites and the main router.