The issue of tempo compensation has occupied many of us in the roll
scanning fraternity but there is no single answer because it's not
an entirely physical or mechanical problem.  Musicians are, of course,
acutely aware of the tempo of their performances and many of them would
have observed that their recordings accelerated in a manner which they
hadn't intended.

There can be little doubt that some of the more savvy performers
attempted to compensate during recordings.  Josef Hoffman, who was
very technically minded, was well aware of this issue and he, for
one, is known to have adjusted his playing tempo to compensate.
Others probably tried to do the same with varying degrees of success
and many accepted the issue as a weakness of the systems and ploughed
on regardless.

The bottom line is that, although it's very easy to provide progressive
compensation during the scanning process, there will never be a "one
size fits all" solution.

Richard Stibbons
Cromer, Norfolk, England