Hi David,
Here’s my recipe when I edit 1080 60i and author SD DVD with FCP, Compressor and DVD Studio Pro.
1. Edit in Apple ProRes422
2. Export 1. as self-contained QT
3. Compressor: Encode 2. as Apple ProRes 422 720×480 Anamorphic (Resize: Better, Field Order: BOTTOM FIRST)
4. Compressor (again) : encode 3. as mpeg2
5. Author!
Please test this, I hope this works for you 🙂
Tamaki