The Fusion SE is a great an amazing 2-1 motor/ESC combo using F.O.C. technology to provide amazing throttle response and feel for scale trail trucks and rock crawling.
But there is always one question. What KV should you get?
There is not a major difference in the1200kv or 1800kv versions, with the exception of a little bit more speed for a slightly shorter run time.
For crawling, the "Smaller" the pinion gear size, the better off you will be, and takes the "Weight" of the vehicle out of the equation slightly. Meaning simply, if you gear correctly, the weight of your rig won't matter as much.
The main difference is the overall speed and how fast the combo will use up your runtime. Low speed response, and torque is almost the same and for most of drivers, the differences really do in fact go un-noticed.
If you are not at all worried about wheel speed, and looking for maximum runtime, the 1200KV option is the way to go.
If you've got gearing options and need a little extra wheel speed from time to time, the 1800KV would be the way to go.