As we were familiar with the concepts, the total time to develop Libsafe was quite short. Solar Designer's kernel patch is a very nice piece of work. Clearly these two techniques are complementary. In particular, Libsafe can prevent security attacks that Solar Designer's kernel patch will miss. The concepts and ideas came from the research that was conducted at Bell Labs in the area of fault tolerance and fault injection.
Some people say consider it to be safer.
StackGuard is another fine piece of work. StackGuard prevents corrupted return addresses on the stack from being used, whereas Libsafe prevents these return addresses from being corrupted. The big difference, as we see it, is that StackGuard requires modifications to a standard compiler and recompilation of all applications. As a result, using this technology, it is hard to stay current with the latest kernel and application upgrades. The major difference as we see is that Stackguard requires modifications to a standard compiler and needs recompilation of all the applications.