http://www.sjscycles.co.uk/sturmey-archer-3-speed-rf3-cassette-hub-36...

Since it doesn't have the click box, it might be more reliable (or
less likely to get banged up when traveling). If I were in the market
for a dual-drive setup, I'd give it a try.

Brian

I think the Dual Drive gear range is slightly greater.  If my math is
correct, I think Dual Drive is about 186% vs the Sturmey Archer
177%.

Sturmey Archer a bit more affordable than the Dual Drive.

Sram recommends that you only use their proprietary shifter which is
not designed for drop bars, Sturmey Archer will use other shifters.
Where the link says compatible with standard shifters, I assume they
mean indexed shifters, not friction.

I can't imagine anyone wanting to use this on a LHT or Cross Check,
but I have a Dual Drive on my fold up bike since I can't fit a front
derailleur on that bike.  I use a 8 speed cassette on that bike.  If I
dd not already own one, I would consider this as a viable
alternative.  I wonder which one is stronger?

You could run a straight-block cassette for super-close gear ratios,
and still have a full touring gear range.

I'm sure we can find a way to mount two "front" shifters to make this possible.

How about barcons to operate front and rear derailers, and a left hand
brifter to operate the Sturmy hub?

Of course, you'd want to look at the fine print of how low a gear they
rate (and will warranty) this hub for. Lots of torque going into a
planetary gear hub can lead to unpleasant crunching noises. Been there
done that (with the first-generation Sturmey XRD-8 hub... twice...).

tim