While converting a bunch of songs to RB4, I realized that RB4's engine didn't handle quick gapless pitch change as gracefully as RB3. It will look really weird in some case, and often (not always) crash the game. So if people want to "future proof" their song, avoiding gapless pitch shift is a step in the right direction. Often just a 1/64th gap on each side will be enough to prevent the ugly backtracking tube and the crash.
Here how it was authored
and how it looks in RB4 (game is crashed)