So if you're going to go "down" to add content, it's gotta be down to 3.0a3 rather than 3.0a5.

Yeah, that'll probably work. I've come up with a cunning scheme to make it easier to switch between versions:

1. Install v2.00-final, and back it up to the drive0 partition, using:

# tar cvfz drive0/empeg-v2.00-final.tar.gz empeg

2. Install a bunch more music, while it's running a stable version.
3. Install v3.00-alpha3, and back it up similarly.
4. Install v3.00-nightly, and (again) back it up.
5. Install v3.00-alpha5, and (you guessed it) back it up.
6. Install the latest Hijack.

This'll make it easy to move between releases without faffing about with upgrade files, since only the player and libraries have changed between those versions.