The Castle motors are awesome, the 4 pole has opened up a new market for off road motors. Tekin already has their 4 pole in testing and I am sure Novak could be following close behind. The only issue I see is ROAR events this summer, but if you don't race ROAR no issue. If I had to pick a Castle motor for the SC10 it would be the 1410, the 1415 is more than capable but traditionally the lower KV ratings are more efficient on more voltage. You can stuff a Sky Lipo 3S in there, they are much smaller.

The Viper's not moving from my truck, my runtimes are almost double what they are in the SCTe and it's very smooth, both ESC and motor never break 100 degrees. My 40C packs are also nice and cool, so not much stress on my gear so I am happy.

But honestly it's drop in what ever you feel mixes well with where and what you run. Much less weight restrictions with this truck which opens the door to more options that work well.