Problem (or is it?)
As great as Studio One's mastering integration is, it's maybe too singular. That is to say that you work on a song and throw that to a new mastering project, now that project has that song, great.
But if you later work on another song file destined for the same "album collection" and mix it, there doesn't seem to be a way to directly throw that mix to the other already created project.
When you go to throw a song to a project, list all of the projects in the project directory so that the user can send that mix directly to any mastering project. The mixdown file [i](for the automatic housekeeping bit) [/i]would still be where it is now, under the song folder, it would just open an [i]existing[/i] project and add that mix to it.
The new dialog would be [b]Add To Project[/b], in addition to the current [b]New Project[/b] dialog. Opening the Add to Project dialog would list all projects on the system so you can choose where the mix belongs, which mastering collection to add it to.
Or maybe better, it would be the same dialog with extended options to add that mix directly to any existing project, with the list of all projects to choose from. You select an existing project and it puts your mix at the end of the collection of songs in that project.
The new ScratchPad feature begs for the ability to render all ScratchPads to a new project. In other words, you have a song with 5 different songs and mixes in it, in scratch pads. It would (one by one) render them and put them all into a new mastering project.