I haven't tried to cut vinyl with my Cameo, but I have never moved the rollers for different paper sizes, I always use the 12 x 12 or 12 x 24 mats. I also use the Cricut mats in my Cameo. I think every machine varies just a little bit. For mine, I seem to get a better cut with the cricut mats.
"If a person who indulges in gluttony is a glutton, and a person who commits a felony is a felon, then God is an iron.”
― Spider Robinson