Using epoxy as a filler is a huge mistake; throw out the West System
epoxy.  Your basic premise is correct that mixing the wood dust from
the species you are restoring will give you a reasonable match.
Epoxy is too strong, unyielding and brittle.  It works great, maybe
too good.

Examine why the wood split in the first place.  By putting what amounts
to a rock in the split, it will appear elsewhere.  The epoxy is stronger
than the wood.  Granted that the crack will not reopen, but you are
transferring the problem elsewhere.  Also if you clean up an epoxied
joint after it has hardened with a chisel, you will inevitably chip the
edge.  I enjoy sharp tools and hate to see them abused.

Solution:  Take a page from stringed instrument and carousel animal
restorers.  When a crack appears, fashion a sliver of wood of a similar
species.  Fit it to the crack and glue it with a traditional glue
with the wood dust as filler.  The wood shim will breathe with the rest
of the piece and expand and contract with the temperature and humidity
changes.

Epoxy has a vastly different expansion from wood.  It is strong but it
is likely that the problem will resurface.  Additionally, many antique
carousel pieces were restored in haste with epoxy which does not
breath.  They are typically outdoors which accelerates the process, but
you will often find rot beneath the epoxy because it locks in moisture.

Lastly, color match.  I have seen epoxy used as a filler on fine
furniture and it typically looks like a slug of plastic embedded in an
otherwise beautiful piece.  A good restorer could paint in the grain
and it would not be noticeable, but that's still not the best solution.
When wood is corrected with wood, it is often completely unnoticeable.
It too can be color matched if necessary.

Examine old furniture and you will likely find repairs made correctly.
Some old timers used colored wax to fill crevices and others used
shellac sticks.  These are hard shellac sticks with color mixed in.

There are a number of ways to work with them.  Typically shavings are
placed in the crack and a spatula warmed with an alcohol burner melts
the shellac and it then dries quickly and quite hard.  The repair is
often unnoticeable.  This is how inlays are adhered.

Your original premise is 100% correct.  Use traditional materials to
restore or recreate traditional pieces.  The problem with using
synthetics may not appear in our lifetimes, but they will likely return
in the future.

Bob Yorburg, New York
http://www.bobyorburg.com/ 
http://www.acanthuscarving.com/