Yeah, as an automotive and aerospace engineer I find the bulb theory "interesting". I plan to check my owners manual to see what type bulbs are listed and pull a couple to check. I spend a lot of time on the Web trying to dispel various myths. Most of my time is spent with the vintage Corvette community.
One thing I NEVER DO is kill the cruise with a tap on the brake pedal. I always use the cancel function on the stalk. Tapping the brake flashes a bright red signal to any bandits at your six, and I'm not interested in advertising my control actions.
The cruise control is an example of a damped feedback control function. The speed you set is controlled by the speed sensor on the back of the speedo housing, and any variation in the sensed speed from the selected speed is going to cause the amp to correct, so a sticky cable that causes the needle to wiggle is going to cause hunting/surge, and you are right, this could get the amp into a sweat. Whenever the cruise starts surging, I kill it with the cancel control. I recall reading somewhere that the Merc cruise control system speed can be set in 1/2 MPH increments, and my experience is that it's very accurate at maintaining selected speed, which is not the case for some other OEM systems.
Since my car is going into summer storage in a couple of weeks (I use the Merc as my daily driver in the winter and a '91 MR2 in the summer.). I'll probably buy the cable and swap it next fall when the Merc comes out of storage for the next winter season.