I can confirm the above tests. Running iperf3 between a PC connected to the WAN side and another PC connected to the LAN side I can push gigabit (940+ Mbit/s) speeds in either direction. And it seems like this little monster has power left over while doing so. CPU idle % is at 42-47%, with sirq taking up the non-idle processing power. I recorded this cpu usage while running iperf for 2 minutes, as to get an accurate and settled in CPU usage reading.
Next, I repeated the same tests with SQM enabled on the WAN interface with a limit of 1 Gbit/s. Running cake, I was able to push 400 Mbit/s WAN -> LAN and 600 Mbit/s LAN -> WAN. Unfortunately, I ran into quite a few crashes while doing so. This is a known issue with cake running on mediatek SOCs.
Doing the same tests with fq_codel, everything was rock solid stable. What surprised me though, was that fq_codel was able to perform way better. It was pushing 700-800 Mbit/s WAN <-> LAN with little differences in either direction. I even tried to set SQM to 200 Mbit to confirm that it was actually working, and as expected, I was now only doing 200 Mbit/s, so the shaping was definitely working.
The bottom line is: I can very much recommend this little beast if you are interested in routing high-speed connections through LEDE without breaking the bank with 150-200 dollar routers.