[BrianG]

Your motor will probably stay cooler with 2 speeds and you'll have even better low speed performance, especially since you're using a sensored setup.

And even if you lock the tranny, you can still use mech brakes if the ESC has the ability to disable motor braking.

I've looked at the 2 speed clutch and there is a little round plastic plug that acts like a thread locker for the set screw. If the set screw loosens beyond this point, then it may loosen while running and fall out. Once you get the shifting where you want it, it might not hurt to use a little lock-tite on the set screw...