In the HCH when shifting into S bumps up the RPM's in the engine (with your foot off the accelerator, it's still not using any gas), and also increases the resistance from the electrical component (which means more charging for your batteries). I've never gone into L because that forces an extrememly low gear ratio, only suitable for 15 miles per hour or below. While I agree that S may not hold as well as a classic transmission--auto or manual--it still allows some control in that regard, especially at highway speeds. As I've mentioned before, I've had occasion to drive some of the canyons around my home, and have not had a problem.

I also find it quite fun to drive the HCH on twisty mountain roads. But I grew up near the mountains, so I am quite comfortable with them, to begin with.