"Delta Force, www.DeltaForce.com sells different 12ga loads with special features but they may not be "street legal" in all areas."
I could be wrong about this, but I believe military and law enforcement pretty much stick with plain buckshot when they use shotguns. Personally, I'd shy away from any gimmick shotshells that contain tacks, piano wires, shoot flames, or whatever else. They may be good in theory and do horrible things to watermelons on youtube videos, but I don't know what kind of track record they have in actual serious situations.
You already said that you'd choose buckshot, so I'm not arguing with you. I'm just thinking out loud.