I assembled up the new board this morning, and so far everything is working great. I moved around some of the labeling to make it easier to read and I flipped the ground and VCC pins on the single row male header to allow one to directly plug in a servo into the board. I would only recommend plugging only micro servos directly into the board, anything larger would most likely require a separate power supply.

The updated KiCad board files have been posted to GitHub and I've updated the servo demo for use with the 3.1 board. I did take another shot at trying to get my MG90S servo with it, but no such luck; it really does want the PWM frequency at exactly 50 Hz. I did later learn that unlike the SG90, the MG90S is a digital servo which may explain why it's so picky.

For soldering components on the board I decided to stick to just using .020" Kester 44 63/37 for everything as opposed to using the .020" solder for just the surface mount components and using .032" AIM 63/37 for everything else that I've done on past boards. I got much nicer joints compared to using the .032" AIM solder for the thru-hole parts, I'm not sure if it was due to the diameter difference and/or brand difference.