Wow those maps could be really useful, it's nice to see where everything is in context to each other. I feel like for it to really be of use, we need to find some sort of big glitch or trick, because there are a few stages where the exit to the level is very close to a midpoint of the level.
This version of the game seems to have much better programming than the SNES version however, but to me I prefer it that way. It makes it more rewarding when you actually do find a new trick.
Okay, so looking at the map for disco fever 3, I now see why we're able to get into that gap, and not able to do it with the cymbals. With this particular horn, there is the tiniest gap that's not present in any of the cymbals.
[edit]: I've already found several small improvements that were inspired by taking a look at these maps, so they are actually coming in handy.