Exhaust or jake brake or neither?

Electrix wrote:
You should always manually select the gear when going down a hill, don't just leave the selector in D. The transmission is likely to upshift, instead of downshifting to keep the engine revs high for maximum exhaust brake retardation.

All correct, though a slight correction to this sentence. With the exhaust brake on, as long as you don't touch the throttle, it will not upshift unless engine RPM increases to where it could damage the engine. At that point, it WILL upshift.

But, as long as you are below that RPM, the transmission will not upshift unless the throttle is pushed.

But, I do like to use the down arrow to "hold" a gear-- that way if that gear with exhaust brake on gives a little too much braking and that gear with exhaust brake off, not quite enough, one can toggle the exhaust brake switch on/off/on and won't have the transmission continually up/down shifting.