I had a chance today to test mine out in an SCX10 trail rig with a 35T/3S. Shifts butter-smooth and 1st gear is really nice for steep downhilling, no drag brake needed. Loads of torque for super slow inching your way up and over the rough stuff. 2nd gear has a decent amount of getup and go also. I'd have to say it's probably one of the best upgrades for an SCX10, and it sure is nice to have the option to drop 'er in low when you need to "thumbsup".
What is the recommended shifter servo to use ;-)