chad:
The argument here is:
If you are in fear for your life or serious injuries you have the right to use lethal force.
If you are using less than lethal force you are not in fear for your life and are using 'maiming force' illegally. Even if the round works as intended you could face some serious legal quandaries. In most cases you can not break a robbers knee with a baseball bat if he is not a threat to your person, same with using a bean bag that is reasonably expected to do some pretty serious, but not lethal damage.
It is one of these really odd results of some serious lawyer-ball. My biggest concern with rubber buckshot is how much will it bounce if any of the pellets miss. My dwelling has plaster walls with wood floors. I have no idea how may times those rubber pellets would bounce in a room before stopping. Are they going to hit me? are they going to hit the BG in the face? Are they going to hit a guest? I won't even get into the possible collateral damage considering windows and tvs.
On the FBI tests:
They were looking at penetration necessary for shooting into cars, shooting at 30 yards, etc., not a guy across the room. The amount of penetration necessary for such things exceeds my need in HD.