An interesting and wide-ranging interview with pianist/conductor Daniel Barenboim is found online here.
A shrug at the HIP crowd: "Those who argue for strict historical authenticity balk at his approach to playing Bach, for instance, to whose piano works he happily adds extra bass octaves. "You have to take into account that it was not written for the Steinway of the 21st century," is his response, "so I think it's perfectly legitimate so long as it fits stylistically. But all these rules about original instrumentation and composers' intentions - it has become an ideology. That's no less dangerous than a fundamentalist state. It gives an answer to everything, even when there is no question."