We used to have a really nice downhill test run in the Mt Disapointment area, not far from where I live.
Not scary as it's safe if you get a bit of speed up(which the D1 tdi auto would), but easy peasy if you start with the handbrake on, and release it just enough to allow you to creep down(with the brake still on just enough to allow slow movement.
Done in the wet and dry, and no problems. So that's my method now on very steep descents where it may get too much speed up.
The Tdi would then max out and hold 3500RPM in 1st low .. whatever speed that equates too. Did feel a bit too fast for my liking tho.
So manual in those situations is more ideal, but can be compensated for.
On most other 4WDs tho where the handbrake operates on the rear axle .. I wouldn't trust that method.
For me, the only true downside of an auto is that you can't push start an auto if (say) the starter packs in, or battery(s) all give up or whatever and you're stranded alone miles from anywhere.
What feels like a million moons ago, I once ran out of fuel in my RRC(which I changed it's LT95 to an LT77) manual.
I had broken leg and wrist at the time, and didn't fancy the 1klm walk to the servo to get some juice.
So I just ran it on the starter(I had dual batteries) got a slight amount of momentum up, third, slip clutch, more starter .. etc, etc.
Got to 50m at an intersection, pulled up .. made the walk (with my broken leg) a lot easier(ie. 100m all up, and not 2klms!).
Probably wouldn't do that if it ever happened again without the extenuating circumstances, but just to highlight the downside of an auto.
With all that tho.. still prefer an auto in a D2 tho.
In a Defender, I'd probably prefer a manual .. probably just a psychological thing.
All the manual Landrover products I've driven .. I don't think the shift quality of the manuals would rate as mid range, compared to many other vehicles.
Best gearchange was sisters little Polo .. clutchless power shifts perfectly, and had to drive it across town(ie. Melb) about 40+ mins with a snapped clutch cable.

