I've been ruminating on this for quite a while, that at ranges from 25 to 75 yards, using the sane length barrel, a .44 magnum with full house loads and comparable bullets will have the same terminal performance as a .454 Casull with heavy loads. I have had many .44 mags and 3 different .454 Casulls and can't see that the extra velocity and even some extra weight in the Casull under the same circumstances as mentioned above make a large "practical" difference. A 300 to 320 grain .430" dia. bullet at 25 to 75 yards with a wide flat nose bullet will penetrate deeply enough to fully penetrate a large game animal's body at a velocity of 1250 to 1350 fps. A .452" dia. bullet of same construction at a weight of 300 to 360 grains at the same distance will certainly do the same. There may be some additional shock involved with the slightly (.022") larger diameter striking at an additional 100-200 fps, but the animal will still be penetrated the same, hopefully through vital organs.
Even at a raking angle, the .44 mag at the ranges mentioned has great penetrating ability. Where the .454 Casull has an advantage is shooting at farther distances, say out to 150 yards if the shooter is capable of making proper shots. Otherwise, all I think it gives you is more recoil, muzzle blast and the need for more powder.