I have made several down sleeping bags and quilts. My preference is for the sewn in individual mesh baffles: separate baffles, not the sewing of a continuous mesh panel to alternating sides. The latter adds unnecessary weight for no particular advantage. As for the material, I have always used ripstop nylon and no-see-um mesh. You have to look at the outside material to be sure it will be reasonably down proof; having one side calendered helps a lot. Most recently, I have been using the 1.1 oz per square yard ripstop. I don't know anything about Dryloft so can't help you there but the taffeta sounds heavy. In my experience, sleeping bag durability is not particularly related to the fabric; it is much more a function of the care the bag receives. Frankly, I don't know why you would need something more durable than no-see-um mesh for the baffles; I have never had, nor heard of, baffle failure when using this material. Usually failures originate in the sewing, not the fabric. You might try Quest Outfitters for the material you mentioned.
May I walk in beauty.