2016 RAM Super Ike Gauntlet

Cummins12V98 wrote:
When descending Ashland pass coming into Oregon on I-5 for example with full EB and TH on I set cruise to 55 and lock out 3rd gear with 33K combined weight and it holds down the pass no problem. I am running in the high 2K rpm range. If I choose 4th it will hold most of the way but will creep up and need to touch the brakes lightly and hit resume on cruise.

EXPERIMENT is all I can say. We humans can SEE what's in front of us.

And also personal preference. In the situation you describe, I wouldn't reef on the engine at near max rpm just to save a tap or 2 on the brakes.
The capability of the new pickups gets more impressive every year, but now it's a contest to see who can get to the bottom without ever using the service brakes?
I'm more inclined to pick an option that is in the moderate range of all systems, rather than maxing out one and not using the other.
Now if you have to ride the brakes down in 4th, then by all means, use all the engine braking rpms you can in a lower gear to save your brakes.