Just kinda reviewing this post.
I see we have two aspects that we are discussing. The G3X will adjust the rate at which the trim will move and its based on the airspeeds that you program in as when to move fast and when to move slow when you hit the switch. The G3X wont actually auto trim unless you have the AP as I believe Brian states how Dynon works. What the Garmin lacks is the amperage needed to drive our Pitch servo motor hence the Safety Trim Booster.
FWIW the Vertical Power unit also has the "trim rate" function for low and fast air speeds.