2000.01.20 17:05 "RE: Unicode build of libtiff?", by Eric J. Schwertfeger
Nope! UTF-8 encoding is the same as ASCII for all values <=255, so all Roman/Latin based language information would look and act the same. For other languages (CJK, being the big example) a non-UTF-8 savvy reader would simply display strange looking values but would be able to handle it OK.
The values are the same, but the encoding is different for values >127. Still only an issue for accents and such, to the best of my knowledge.