Expansion is good but the thing that i really like is how accurate they are.
I make 150 rounds. We tested them with a friend with a Glock, a HK USP Expert and a SIG. All same caliber 9mm para.
We are no experts or have the super equipment for testing and getting all the real results but we have found that they perform better.
They think that hollow points are better for practice and all that, so they will stay on the sand, wood or won't bounce that bad if they hit steel or something else.
About defending your self...... Europe in general have no respect for human life and private property (my opinion) but that is another topic.