[sciurius]

Interesting...

I think most of it stems from the practice of transposing by interval instead of key. When you say "I have a song in A, and I transpose it to B" the process is, indeed, deterministic. However, when you have a bunch of chords and want to transpose up 2 intervals, the case is different.

I'm one of those stupids that transpose by intervals. I also play Bb instead of A# and C# instead of Db...