Dedicating all four cores to one WU will definitely earn a bigger bonus than allocating only two. More than 2x based on the way the formula credits for fast returns.
Having said that, two cores are certainly capable of earning SMP bonus on the current WU's. See Foldy 7, blade 2 for example: »foldy.nozero.org/drop_box/data/F···Hlog.txt--
Hello, my name is Bill and I'm a crunchaholic...
Proud to be hosting six Crunchenstein blades, and three Foldinator blades