The pants are sewn through. You can make them baffled and it wouldn't have been that much more difficult just alot more time consuming and heavier for no good reason. I modeled this after the specs for the WM flash and flight pants. They are somewhere right in the middle taking features from both. I started with a green peppers fleece sweatpants pattern from JoAnn fabrics. Sized up a few sizes and added about 3" to the waist of the pattern so that I would have enough extra for loft and to fold over and make the synch waist. I think the pattern worked out ok, by the end I could tell that it wasn't meant for multilayer pants, my seams weren't lining up at all towards the end.
If I ever make another pair they will be 2" baffled, 5-6 oz of down, and the correct zippers to make them full zip.