So here's my proposal: Make folder tracks, as others have suggested, and include a "comp" option in the folder properties. When set on, it does several things: (1) It only allows one track in the folder to be selected for playback over a specific time interval. This way you don't get any unwanted doubling. (2) It automatically selects zero-crossings and automatically crossfades when switching between tracks, to minimize clicks and reduce overall work time by a lot. (3) It color-codes takes and grays out unused portions.
It's kinda confusing, so here's a photoshopped example showing how one would comp a guitar using this method:

The more I experiment with Tracktion, the more ways I find to make my work easier. I know this option isn't totally necessary, but I would love a feature like this and would use it constantly. I think it still fits with the Tracktion interface too. Any thoughts?

