Anton Berlin wrote:
... I want to simplify and feel that I could get
practical and get down to one bike and be content with that.

My current idea is a titanium cyclocross style bike that uses mtb
wheels, has a long wheelbase and is set up for touring (fenders,
panniers, etc) would be the best compromise of all worlds.

I want a bike that is flexible enough to ride everyday, tour
extensively on (already have 2 cycling trips around the world and
multiple through Europe)

The open questions are rim brakes or discs ? Derailleurs or internal
gearing (rohloff or sram) ?

And the pros and cons of using s&s couplers. Thanks in advance for
your thoughts and input.

It depends on your planned uses, of course. There are many styles of
cycling.

Titanium is fine. So are several other metals. A benefit of steel is
that it's easier to modify later, if necessary - adding brackets,
changing spacing, etc. If you don't see that happening, titanium is fine.

Cyclocross frames may feature high bottom brackets. If your frame has a
horizontal top tube, that may reduce standover height. You can decide
if that's a problem, depending on your use. For my road cycling, I
prefer touring geometry.

I've heard that mtb tires are more available, worldwide, than 700c. If
you plan on more super-remote riding, you may want to check out that
issue. For my riding, which is mostly on-road and more civilized (North
America & Europe), I like the greater selection in 700c road tires. You
can get them fat if you need to.

I'm not a disk brake fan. If I rode mostly off-road and/or did more
huge mountain descents, maybe I would be. But cantilevers are more
robust in that they are universally understood, parts are everywhere,
they work with any wheel, and they can be repaired on the road with your
multi-tool.

Rohloff vs. derailleurs? I like low-tech. I know Rohloffs "never"
break - but my derailleurs have almost never broken either. And I can
fix a derailleur.

I have friends with S&S couplers. They love them. Of course, they're
worthwhile only if you ship your bike often, e.g. as luggage. By
comparison, I've found packing a standard touring bike for air travel to
be a major hassle. For air travel, I prefer a folding bike, but I
probably wouldn't want it for an only bike.

--
- Frank Krygowski