Do pumps inherently kick more than comparable over/unders and semi-autos?
Well, yes and no. Any shotgun other than a GAS OPERATED semi-auto will seem to kick more than the gas operated semi-auto.
The reason for this is that as stated numerous times before, recoil is recoil. The laws of physics will not be denied. However, the way we human beans perceive things can be well very subjective. Brister in his definitive work on shotgunning,
Shotgunning, the Art and the Science, discusses the subject at length.
The gas operated auto loader, because of its gas piston, the bolt moving back, etc. causes the recoil albeit the same as from any other gun to be delivered as a series of pushes spaced out over time (a very short time) rather than one sharp smack. Thus, while it is really the same, to the human brain, muscles, nerves, etc. it feels like less.
Now there are all kinds of factors at work here. Fit is certainly one of them. An ill fitting gas auto loader can be painful to shoot. A perfectly fitting pump can be a joy. Then there is technique.
If you don't have your body in a position to be a spring rather than a board any shotgun can be uncomfortable.
Gun weight is also a factor. Heavier gun, less perceived recoil.
The point is that PERCEIVED recoil is very subjective. That being the case, you will get all kinds of answers here. Some guys will swear that their Remberg 570 with no recoil pad is the softest shooting gun on the planet. Some will say that their uncle Jakes 12 ga 11-87 will tear your arm off.
That is their perception. Who am I to question it? I do know that x amount of powder behind x amount of load will deliver x amount of recoil. Strictly from a mathematical standpoint. How you perceive it from a particular gun can be totally different than the way I perceive it.
With all that BS out of the way, most folks find gas operated auto loaders to be the softest shooting of the various types of shotguns. I know I do.