I hope you can all stand one more input about Mylar for music rolls.

Several years ago I visited Allen Miller (near Hartford, CT) who was
involved with the resurrected Austin Quadruplex perforating equipment
in the 1970's.  They had experimented with Mylar for their recutting
and found (in addition to some of the problems already mentioned) that
the punchings were prone to static electricity and almost impossible to
clean off of the Mylar roll after perforating!

They too gave up on the idea and stuck with good quality paper.

Cheers,
Rob DeLand - BluesTone Music Rolls
http://www.bluesrolls.com