Oh boy! I am numerous rulers and 4 cutting mats and I intermix them all the time. The stars must be all aligned as I have not had any trouble yet with my piecing so I must be doing something right. I will try and stick with the same ruler/ruler maker for my next project - having said that somethimes a smaller ruler works better after the large piece has been cut. The most important thing is to have a sharp blade! I try to stretch my blade useage far too long sometime.
I perfer Creative Grids ruler I wore the markings off my Olfa ones.