Perhaps I'm simply being obtuse, but I would hate to miss an opportunity to learn something...
Are we speaking about Hill Start Assist, or Hill Descent Control? I was actually unaware of the Hill Start Assist feature until just now, however the Hill Descent Control
(button as it exists on my dash shown belowI've used several times in some pretty hairy spots, and it works both uphill and downhill very well.
Jeeps manual defines them as follows:
Hill Start Assist When equipped with an automatic transmission, this feature prevents the vehicle from rolling away when starting on an up- or downhill gradient. It holds the vehicle stationary for 2 seconds after the driver's foot is removed from the brake pedal, allowing time to apply the throttle
Hill Descent Control HDC is only intended for low speed off-road driving.
HDC maintains vehicle speed while descending hills in off-road driving conditions by applying the brakes when necessary.
Thanks in advance for clarification