Okay here is my unscientific test results.
Had 2 boxes of each.
4 trips to Ridgefield--amazingly all out of blind 11.
3in 1 1/8 oz #2 shot
First--- I have killed 4 times more birds with fasteel than All purpose. Could be me,

or the shot. Most of my days seem equal on my effort.
second--- same range--birds die with fasteel--fly with all purpose.
Third--- Took the shells apart. Weights are in gr, because thats what my scale does.
Here goes------------
Fasteel 21 gr powder all purpose 17 gr
bb count 126 135
bb size 3.81mm 3.68mm
total wt of bb's 488gr 462gr
so there you have it.
My personal experience: Fasteel kills more birds.
I have not patterned both , yet.
I shoot a modified choke.