After reading this thread, I'm a little confused as to what is happening (or why it is happening) in terms of the 8-speed transmission "dragging" on descents. I agree with skytop in that I would also find this characteristic "obnoxious and annoying".
these transmissions downshift the moment you take your foot off the gas. You must drive with your foot on the gas ALWAYS to prevent the OBNOXIOUS and ANNOYING downshifting.
I suppose that on very steep descents, having the transmission automatically downshift would help to save the brakes but on more gradual descents, when I may well want
to "coast" to save on gas by not going to a lower gear, I would object for the transmisson deciding for me. Going to a lower gear (higher rpm) when traveling downhill will generally use more fuel than if you stayed in a higher gear and braked judiciously. I mean you can always downshift manually
if you see the need. I'd prefer that decision to be mine.