I have a 12" long ruler with the quarter inch lip, also 2 of the 6" with a quarter inch lip and a 6" ruler with a 1/8" lip. It depends what block I am making, they all have a use! I sometimes wondered at first if the 1/8" seam was strong enough but it is.
It has been a few years since I have done some serious PP but am looking forward to it again. Still haven't found the 30's solids and my book hasn't arrived yet.