I used Plex for years, and it is the superior product (if you pay) compared to Open Source alternatives. However, after seeing Plex’s recent incentive pivots and looking for investors I jumped shipped to Jellyfin. The thermometor of enshittification is indicating that Plex is on its way out.
Folks who haven’t looked at alternatives yet, do so now.
There is no double nat. Passthrough mode has worked as expected for me. The one issue I have is that the RG will maintain firewall states, so it limits you to the RG hardware for those states. I have a pretty large home network though, tons of devices, IoT, etc, and it has been stable.
Latency seems decent. I have an AT&T fiber 2gb symmetrical connection and a ping to google from my Netgate pfSense machine is around 10-15ms.