The following ignores anything regarding temporary wound channel/cavity. It's not relevant to handgun bullets that do not create hydrostatic shock.
How is this so? One would think that if a cartridge does not create significant hydrostatic shock, frontal area would be of paramount importance in the discussion of wound channels or crush cavities.
The question being posed was: so .44 spec is as good as .45 acp?
If you read the post, you saw that I compared and contrasted the above stated cartridges and came to the conclusion that they very similar.
So called hydrostatic shock is not terribly relevant in discussing low velocity handgun cartridges/bullets and I did not referance hydrostatic shock, but rather frontal area.
Unexpanded, .45 (.452) caliber bullets have a frontal area of: .64 in
Unexpanded, .44 (.430) caliber bullets have a frontal area of: .58 in
Thus, given bullets of equal weight and at equal velovity, and similar design and construction (i.e. .44 Kieth bullet compared to .45 Kieth bullet or Hornady XTP to Hornady XTP), .45 bullets will make slightly wider permanent crush cavities or "wound channels" than will .44 bullets.
And .44 bullets will, given the above criteria, penetrate a little deeper.
Wound channel may not directly correlate to caliber, however it does correlate, your comparison of 9mm and .45 bullets is a fine example.
.451 bullets = .63 sq. in of area
.355 bullets = .39 sq. in of area
The .45 bullet being 61% larger. The numbers you gave for wound/crush channels, .3" vs .2", again a 66% difference. So caliber and wound channel, all other things being equal, must be at least roughly analgous.
But now we are splitting hairs, as is the difference between the .44 Special and .45 Auto.