I have never personally tested them, but others have and found that they are poor in the penetration department. They make nasty, shallow wounds, but I'm afraid they don't offer adequate penetration to cut it at as defensive rounds in my guns. I prefer to follow the FBI guidelines when choosing ammo and find a round which offers good expansion and penetration (12" or more in ballistic gel). Several rounds including Winchester Ranger, Speer Gold Dot, Remington Golden Saber and probably a few others usually do well in this regard. They also fair better than most rounds when having to penetrate through several layers of clothing.
While the development of Glaser and MagSafe ammo was an interesting one...in that new bullet designs and technology were being explored, I think it's best in the meantime to stay with something a bit more conventional. Any of the loads mentioned above should be capable of getting the job done if called upon to do so. A defensive firearm is really part of a system. This system is the weapon itself, the ammo and most important of all....the shooter. So practice shooting regularly, maintain the weapon, and feed it good, proven ammo. That's about the best advice I can offer. Hope this was helpful to you in some way or other.
---Charging Handle