So has anyone done a throttle-spring unwind? I did that in my FJR-1300 15 years ago because it had a monster hard throttle pull. It made a major difference in surging at low speeds because you could control the throttle much better.
The procedure was to pull the spring end off the stop with a needle-nose, let go, and in a nanosecond it would unwind one turn and click back onto the stop.
My VFR is still virgin and I haven't even gotten the tank off, so I have no idea how difficult this would be to do.
Varying spring tensions would explain people's varying experiences whether they have the problem or not. I have a '17 DCT that I bought a couple months ago (Dec 2019) and it definitely has the problem.
I do notice it's really a result of the arm posture. On my VFR, my arm is mostly horizontal and held up by just my posture, so when I hit a bump, it does kind of flap, which feeds into the throttle. On my other bikes, it's the sportbike posture where your arm is 45deg and you're putting your weight on it, so bumps have little effect.
I have a Kaoko that I'm installing right after posting this.