I think you first must establish criteria to evaluate SD ammunition. These threads always generate posts where people list the round they carry but don't list the reason why.
I think to go about selecting a self-defense cartridge, you have to gain an understanding or at least form a belief about what causes incapacitation.
For myself, the number one criteria for an SD cartridge is that the bullet must penetrate sufficiently deep, under a wide variety of situations, to reach vital tissue.
The Liberty ammo fragments with most of the petals / fragments stopping short of 5 inches. The remaining base tumbles and usually stops short of 12 inches.
After you form a belief about what cause incapacitation, you have to make a decision about what situations you want to be prepared for, how much of the bell curve you want to cover with your firearm and ammunition. On one end of the spectrum is a frontal shot on the skinny guy wearing a T-shirt. The skinny guy is 11" from front to back - not much muscle, a frontal shot with a 30gr copper disc that penetrates 10" is going to reach vital tissue, given proper shot placement. On the other end of the bell curve is having to take a cross shot on a barrel-chested, muscle-bound thug wearing a jean jacket over a shirt, and a T-shirt underneath that. Will the base of the Liberty bullet go through a jean jacket, a shirt, a T-shirt, a bicep, another layer of T-shirt, another layer of shirt, another layer of jean jacket, another layer of jean jacket, another layer of shirt, another layer of T-shirt and still reach vital organs?
Tests in denim covered gel predict that it won't.