Roy,

The former sounds simpler. Are there advantages to
the latter?


It IS simpler. WAY simpler. And I would recommend to go that way for
occasional flying in the US. Mind you, the certificate holder will have
to do a full flight review, often forgotten by FBOs renting to
foreigners. If s/he is not familiar with US airspace, regulations and
procedures (radio work, above all), and the CFI giving the review is
halfway responsible, this will take more than an hour ground school and
an hour in the air.

The advantage to the "true" US certificate is that you can build
ratings and new certificates according to US standards on it. Also,
should your underlying foreign license become invalid for some reason,
the US certificate based on it would become invalid, too. One very
important possibility for that scenario lies in the extremely strict
medical requirements for private pilots in some European countries,
e.g. Germany. It's quite easy for a pilot to have his German medical
declined on a condition that would be perfectly ok in the US. Allowable
uncorrected vision, for example, is limited in Germany, it isn't in the
US.


--
Thomas Borchert (EDDH)