What I have noticed is that banknotes tend to move in the marketplace along with coins, and artwork for example. Especially in times of downturn, when people look for more certain investments, such as a Picasso or a even much more beautiful note from the early Bank of Canada series, or Dominion of Canada.
(Yeesh - what would anyone do with a painting??
)
Unfortunately, to an insurance company, a 1935 $500 is worth $500 , because it is cash (please someone correct me if I am wrong). But still any rare note would make a great long term investment in my opinion.
All for now,
Hudson