The main difference between belt and chain (aside from the fact that
belts are usually quieter) is that there will be definate unignorable signs
that something is wrong well before the chain breaks.

   Engine rattle upon starting that goes away after a few seconds, knocking
upon acceleration/deceleration, valve noises, excessive oil consumption,
rough idle, difficulty starting, etc. are all things that will alert the
owner to have the vehicle checked.

   Belts will often fail with no warning at all, and when there are signs
they are subtle and easily dismissed as something less important.
Inspections don't always tell the whole story as the belt can look fine from
the outside, but be frayed and ready to break underneath where it cant be
seen.

   It just seems foolish to me to pay $200 to $400 to have a $30.00 belt
replaced, when the only real benefit to having that belt instead of chain is
a little quieter engine.  Add to that the risk of complete engine failure
when a belt breaks on cars without free floating valves, and there is just
no upside at all to belts.

Bob