In my experience, engine braking only happens if you aren't using the electric mode enough. The idea is to charge to full with low gear and then expend as much of the battery as possible with max electric power.
That's not the only reason you would use low. Many others have reported using low continuously with no issues. Its useful for max regen and simulated one-pedal driving. I do with it would illuminate the brake lights when braking this way, and in my part of the country especially at this time of...
Has anyone experimented with highway/city driving in eco/slippery mode in "low gear"?
I would assume that slippery in normal gear would be best for highway driving, while stop-and-go city driving in eco mode with "low gear" could be better.
Would be interested to see some controlled tests...