remember, shortening a barrel by half is going to greatly reduce the velocity of the bullets being launched, AND more still burning gunpowder is going to fly out of the end of the gun.
here is why this should be important to you. A hollowpoint bullet needs velocity to properly expand. The shorter the barrel the less likely that the hollowpoint will successfully work. That alone should make you use the longest barrel you can.
Second, the still burning gunpowder will make a big muzzle flash, which can damage your night vision quite badly if you do have to use the gun at night.
Further, a longer barreled gun has a longer sight radius. Long barrels do no make a gun more accurate, they make it easier for human beings to shoot them accurately. Now, in truth in a home defense situation, you will probably revert to just 'point shooting' but still the ability to aim more prescisely should count as a plus
Finally, I believe the snubbies you describe are both 5 shot models, I'd take the extra shot.
The only reason for a snubnose barrel is to make the gun easier to conceal on your person. Unless the 4 inch model will not physically fit where you are attemping to conceal it next to your bed (unlikely) stick with the longer barreled model.
As far as the 4 inch barrel being possibly easier to wrestle from your grasp, by the time anyone is going to be attempting to wrestle a gun from my grasp, that gun is going to be empty. Both models are equally vulnerable to someone clasping the cylinder or hammer area to keep the gun from firing, barrel length has no play there. Gun retention in combat is more a matter of technique than gun size. If you are in real close quaters, wrestling distance, hold the gun back with your main hand, hold it about at your hip or ribs, and have your left hand and arm ready to push the person back