"using an 8spd bar end shifter with a travel agent was in vogue for a
while - it actually works great."
It does not, in fact, work great, but some may find it adequate. We
set one up awhile back, and it shifted, but the shifts were not exact.
It could be tweaked to shift better at one end or the other of the
gear range, but there was always some compromise. Friction-mode
"seemed" fine, but I have no idea how it would work in the long run.
At minimum, I suspect it voids the hub warranty. Jay at Jtek explained
to me that Alfine/Nexus shift stops are not uniformly spaced, while
standard indexed bar-end shifter have uniform cable pull from one gear
to the next (regardless of whether you use a travel agent). At best,
the travel agent set-up hits the gear more or less correctly "on
average". Anyway, I concluded that it was a fun experiment, but that
I would never sell this set-up/kludge to a customer.
(BTW, I'm cringing at the idea of installing one of these heavy/draggy/
hard-to-fix hubs on a fine bicycle like a Rambouillet, which will
require strange cable routing, a chain tensioner, etc. I have worked
on and ridden MANY of these, and still don't fully understand the
appeal for most bikes... What the heck is wrong with modern
derailleurs?)