I used to have the Gerber Guardian. I bought it on a whim before I knew anything about knives. This knife has a couple of problems as a defensive blade. First, the handle is very small and thin. Although it's pretty grippy, I could never get a strong grip on it and I have small/medium sized hands. Secondly, although the blade is secure in the sheath (the tension on the knife is adjustable), the tip of the blade rattles around in the sheath and makes a fair amount of noise - enough to attract attention.
You probably realize this, but the Guardian is a pure self-defense blade, and has absolutely no value as a utility knife.
If I had a limited amount of cash to spend, I'd think about something like the Columbia River Kasper Companion (about $35). The blade looks stronger than the Guardian's, the handle looks a lot more secure, and it probably will work as a utility blade as well.
miguel