So ARM is now on the official stable release? We got one of those SG-1000's. The comment in this article is spot on. We're using ours as the firewall for a Raspberry Pi 3 cluster. ARM end-to-end and under 30W.
Does this mean I can use the RPi3 as pfSense now? Or only Netgate supported?
Should be a yes. But just because you can doesn't mean you should...
In addition to just being 100mbit, RPi3 uses USB2.0 to Ethernet Bridge to support the Ethernet port. Because of that networking is pretty impaired (not likely to reach full wire speed, will be PPS limited on small packets, and bi-directional traffic may be troublesome).
The SG-1000, OTOH, uses separate USB3.0 port from the ARM SoC for the Ethernet bridge for each GigE port. On a pure throughput basis should be able to hit 960kbps (almost 1Gb) pretty easily. Processing the packet filters on the little SoC will obviously prevent full-rate pfSense traffic - but at least you aren't "fighting the wire" like you would be with the RPi3.
BTW, the Odroid C2 also uses the USB3.0 port for its GigE Ethernet bridge. So if you want pfSense in an RPi form factor there is a path. Assuming, of course, you can get BSD/pfSense to load on the Odroid. The Odroid XU4 might make a good choice too - but the kinda odd Big/Little core design might make BSD/pfSense support even more difficult.