IMO anything birdshot can do, buckshot can do better.
Also, to me the whole over-penetration thing seems to be blown way out of proportion. First of all, if you just hit what you're aiming at then over-penetration does not matter. A miss with birdshot is going to be way more dangerous than #1 buckshot (my preferred HD load) that hits the bad guy. Even if #1 buck does penetrate all the way through the BG and through a sheet rock wall it's going to have lost so much energy that its going to be no more dangerous than birdshot that misses.
The way I look at it, a person shot with birdshot MAY CHOOSE to stop after getting hit. However, a person shot with buckshot will usually have no choice in the matter.
"It's not the bullet with my name on it that worries me. It's the one that says "To whom it may concern."