I switched to the smaller W/C in the rear when I did my 11.75 disc swap.
I have 11" drums and they still lock up. Currently have 2.5x11 and switching to 2x11 pads for less surfacing area (not changing the drums).

I would think 2 larger pads would "grip" more. If the 2x11s don't fix my problem maybe I'll try using 2 of the smaller 2x11s on each side.