What do you mean by firewall, exactly? I do nothing extreme, just an pf or iptables ruleset, run dnsmasq, privoxy - those sorts of things. Glad to take some performance benchmarks you can recommend.
The basic stuff: NAT translation, port forwarding, connection rejection and the like.
For bonus points, doing stuff like traffic shaping/prioritizing (like CoDel) at gigabit speed would be rather interesting.
At the moment the EdgeRouter Lite can do limited amounts of packet inspection using the offload hardware. As time goes on the Ubiquiti folks figure out how to better use the offload chip, but -for now- rate limiting and traffic shaping has to run through the thing's CPU, which -IIRC- gives you somewhere north of 100mbit/s of throughput.
> I think it's a good deal compared to something like...
Oh, for something that I would expect to be able to keep using for 10 years, I think it's quite a reasonable price. :D
Edit: Yeah, I don't really have any perf benchmarks to recommend. I guess -if I had the time and the gumption- I'd do something like set up iperf (probably 3 so you can use TCP) on two machines (each in a different subnet so packets would pass through the router) and adjust the iperf listen port so that my various firewall rules triggered, and compare performance.
With both OpenBSD and Debian, I've had no problems routing at gigabit speed locally and the maximum 350 Mbps on WAN.