All righty...on US8 needles, I got 4 stitches/5 rows per inch. Not ideal because it's kinda stiff. But :doh: after I knit that swatch I looked up what my gauge was with Shine when knitting on US6s, and it was 5 sts/7rows per inch (not with the yarn doubled). So that would probably work for your pattern.
I can't speak to whether cotton is good for scarves though....because I don't really wear them. :??