Not so much stronger, as different. To me, a .45 is more of a push back, which is more pleasant to shoot. The .40 is more like the barrel snapping up and back very sharply. I guess that's the best I can describe it.
I've got a 23c and added a heavier recoil spring, and it is much more comfy to shoot than a stock, uncompensated 23.
Maybe others will have better insight.