Ezrun is a great speedo if you're running mild motors I run one in my B44 with a LRP 7.5t which is about the same KV as the Hobbywing 5.5t.
I run Mambas when I wanna run 5.5t or faster they are great value too.
Neither speedo cogs with mod motors, 17.5t isn't really suited to sensorless.