One of the biggest issues of this ossified study of hundred-some year old music is that our university students are being taught that Beethoven, for instance, is forever... or at least his music is. We play them wonderful excerpts recorded on Steinway 9-footers of his Sonatae, and it never occurs to the young initiates that this music invites a more curatorial perspective. Jan Swafford at Slate has a wonderful article with sound examples of the difference a period instrument can make. After all, Beethoven had only 5 and a half octaves, and timbres that varied widely! No wonder he treated each hand as a different instrument -- the timbral differences in the high and low ranges made them sound quite constrasting indeed.