Chef.
I have the system I described above and don't see much windage, I think its pretty negligenciable.
My sail once inside the bag and the zipper closed flattens out and its not that bulky.
I do admit the bag is ugly and I don't like it and it affects performance as it "bolcks" the lower end of the sail. I use it when I cruise with the family where I need to single hand for a month and half, and admit the convenience is wonderfull.
It is noisy, but I solved the problem by keeping it snug, and by tying the front end.
Once the sail is closed, I lift the boom slightly to flatten the bag even more, because that removes tension from the lazy lines.
