This weekend, I finally got a chance to mess with this some more.
I was able to borrow a Netgear GSM7312 switch from work. While the GUI is laid out differently from the GS108T, it follows the same unintuitive logic. Fortunately rhornsby created a great guide for the GS108T that I was able to follow to get the 7312 working.
When I was directly connected to the 7312, I was pulling ~930 mbit in both directions. That's about as fast as I've seen any Google Fiber connection go, so I'm really pleased.
My pfSense box is a rebuilt and upgraded Watchguard X5000. With that in place, I'm seeing around 800 both ways. So a little bit of loss, but I'm still pleased. Especially for something that didn't even power up when I bought it. Video is working nearly perfectly. I've seen a couple very minor interruptions, and I'm hoping I can eventually tune those out.
Given what I've seen on eBay, I don't think the Netgear GSM switches are preferable to the GS108T. They can be rack mounted, but they take up more space and power than the GS108T. They're also a bit more expensive. On the bright side, they have a text based command line and config file. I've attached a fairly generic config for my 7312. Port 1 goes to the Google ONT. Port 2 goes to the router. And port 3 is set up to allow you to connect via telnet or the web GUI on 192.168.1.4.
What I'm really curious about is the Netgear FSM series. These are 10/100 switches that have 2-4 gigabit uplink ports. They're quite a bit cheaper than the all-gigabit GSM series. I was able to grab a FSM7328S for $35 shipped. According to the data sheet, the backplane bandwidth is competitive with the GSM7312, and it uses the same base firmware and command line. So hopefully I can just paste in my config file and be right back in business.
Thanks to Atlantisman and rhornsby and everyone else for their hard work on this. It was so well documented that it was actually enjoyable to work on. I should hopefully have a report on the FSM7328S this weekend.