Yeah, I definitely didn't discover it, was just the beneficiary of the forums.
If using a PC-V, ideally, when the PC-V registers a throttle percent, the ECU will register the same percent and it will scale properly though the 0-100 range. For example, on my bike at .60 there's a mismatch, always 3% behind on the ECU vs what PC-V reads because of the dead zone. Each bike will be slightly different, but .63 seems to be working on a lot of rockets.
Essentially, what happens, is the travel between .60 and .63 is a "dead zone" where the ECU sees 0% TPS through the .03 volt area. It results in a "just cracked" lean situation because the ECU doesn't know the throttle blades are opening. It will haunt you forever and cannot be tuned out with compromising the entire 0 and 1 percent TPS columns of your tune.
The effect you'll notice is a slight jerk and decel popping when holding it nearly, but not quite, closed.