Normally I ride it only in the city for easy and fast maneuverability. But this time traveled with friends to Japan that I realized it is also capable of hill climb.(A bit tiresome though)
This Coaster brake will activate when you pedal backward in a sudden. The relative position of left and right legs will generate different braking power (eg. clock face digit 3-9 position will give you most power and 0-6 the least). Hence no big issue to go downhill.
The only trouble with this automatic gear shift mechanism is the timing to shift gear, it will need more time to properly tuned. This SRAM hub detects rotation speed of the wheel to determine the timing of shifting gears（controlled by one spring）.
If installed on small wheel brompton, the spring has to be more powerful in order to delay the gear shift.（This will require a lot of trials and errors for perfect adjustment.） After fine tuned, the rider can apply out-of-saddle position to climb hill slowly.（A bit more efforts than stock 2 speed with 54/12-16）
We rode 60km KM that day, no issue whatsoever on normal road condition.