CDR, answering your questions in reverse order, I haven't run across any actual shootings with Extreme Shock, and therefore can't make any recommendations pro or con. Saw its manufacturer do an impressive demo...am overdue to take the manufacturer up on the challenge to go hunting and kill something with it...but can't comment from any personal or gathered experience.
Staggered loads in the gun? I'm not comfortable with the concept. In more than 3 decades of debriefing gunfight survivors, I can count on my fingers the number who kept count of their rounds after it went past the first few shots. You really, REALLY want to know what's coming out of the gun the next time you pull the trigger -- penetration, point of aim/point of impact, all of that.
If you don't trust your .380 to get the job done with Bullet A and therefore back it up with Bullet B, it may just be Nature's way of telling you that .380 is submarginal for your needs...