As far as I can tell, from the somewhat minimal GUI Tesla gives you, and the general feeling while driving...
You can "coast" with regen on, you just need to balance the accelerator at the point where you aren't adding power, but the car isn't taking power away.
You won't see any green or black on the power usage bar.
Coming down long mountain roads, it's somewhat easier than coasting in an ICE and having to continually shift down gears or ride the brakes (which is obviously bad).
This seems insane to me. "Do nothing and the car coasts" versus "balance this pin and the car coasts" is such a massive dichotomy shift that it seems like poor design. It's a car, not a helicopter.
You're massively overestimating the level of effort needed to hold the accelerator steady. The software seems to understand your intent and will help keep the speed relatively steady. Its not like making a millimeter adjustment of the pedal adjusts your speed by 20mph. It took me only a few minutes to get used to it. I'm able to keep a far more even average speed in my electric car than I am my ICE car, as now when I start getting off the gas it actually starts to slow down instead of coasting meaning I'm exerting more control in one motion instead of having to make two motions to achieve the same effect. I'm also usually smoother at slowing down in an electric with heavy regen. I never have to switch between accelerator, not pressing any pedals, to braking. Its just smoothly getting on the accelerator, holding it when I'm at the speed I want, and then slowly getting off the accelerator when I'm wanting to slow or stop. Then once the car stops I take my foot off the pedal and the car holds itself in place.
You're still thinking of pressing the accelerator as "open the throttle on the carburetor this much". On modern cars these days, pressing the accelerator is really more like "I'd like to go this fast", especially in electric cars. Its a vastly different experience.
I don't think I've actually touched my brake pedal in the last 2,000mi in my electric car, and I drive almost exclusively city driving on it.
You can "coast" with regen on, you just need to balance the accelerator at the point where you aren't adding power, but the car isn't taking power away.
You won't see any green or black on the power usage bar.
Coming down long mountain roads, it's somewhat easier than coasting in an ICE and having to continually shift down gears or ride the brakes (which is obviously bad).