I'll take a stab at this since no one else has yet.
I don't know what is sufficient for the application because there is no application information... Then I still probably wouldn't.
CSM, as a mat, usually has a binder that holds all the pieces together and the binder is dissolved by styrene, a product not contained in epoxy. Therefore the binder is never dissolved using epoxy and the fibers never come loose to make fitting work. There is also some sizing compatibility that causes the resin/fiber bonding to be less than designed. Stitch mat and some combination products don't have that problem because they're not glued and are therefore compatible with epoxy. Most combination products that my supplier provides are epoxy compatible.
I don't think you will see a big difference laying 1208. It's a little bit stiffer but harder to pull out of shape.
Can you use 1200 where 1208 is specified? I had this discussion with Graham. I heard from others in the business that combination textiles are hold overs from polystyrene products and the mat has no place in epoxy construction. Graham's response was that while it's true that you don't need the csm for peel strength, it does help getting glass fibers packed closer together and it provides some off axis strength. But in the end he said that if the csm offends me I could use 1800.