I'm surprised that on one has responded to this yet!
Often this question gets some quite strong opinions on the board (perhaps mostly found in the old forum?)
I have a concertina with brass shoes, one with aluminum, and can tell little difference that can't be attributed more to layout and design rather than materials. The accordions I own are all constructed with aluminum shoes... from a 1940's Hohner, a 1950's Bell, and a 1990's castagnari and the tonal characteristics are all over the board, but none seem to suffer from the use of aluminum. Dipper uses aluminum on some reed shoes, brass on others (at least on the very, very few that I've encountered, those lucky folks!) so my suspicion is that it's not as significant as it's been made out to be.
