I think longer, conventional rifles are so much better in this regard for the simple reason that they have a higher "polar moment of inertia." This speaks to the amount of energy needed to change the radial position of something, as it is a measure of the inertia of the object around an axis, not just in a linear manner - which is the only way most people think of inertia.
Think of it this way - if you have a three foot long dowel rod and put two one-pound weights on it, but allow those weights to vary in location, you get very different results even if the system balances the same. Put the weights in the center six inches apart, and then compare that to having the two weights at the very ends of the rod thus far apart - both will have the same balance point, but the one with the weights in the center will be "twitchy" to keep pointed in a fixed direction compared to the other.
This is really just a deeper dive into MysticalDragon's point about weight distribution . . . .
I find my most stable, easiest to shoot offhand gun is my Daystate Air Ranger, followed by my Marauders. My Huben (which I love) and my Sidewinder (which I am warming up to) are much harder to shoot as well as I find them to be "twitchy" - they deflect off the aim point much faster and easier than the Air Ranger.