I'd like to know too how they can confidently state that Earth's orbit does not change. Would it mean we'd spiral into the sun or out of orbit if it did?
Oddly enough it's pretty tricky to steer the Earth into the sun as well, but we should be losing minute amounts of energy that will eventually put the Earth closer to the Sun. This probably won't happen before the Sun explodes though.
The entire Earth orbits the Sun at 67,000 mph -- around 67X faster. And note that it is the entire mass of the Earth moving at that speed, not just the equator.
Changing the rotation speed by 1% is a whole lot easier than changing the orbital speed by 1%.