A definite zombie thread resurrection... cool.
When it comes to knife balance in general, I find that the proper balance for a particular knife varies with its intended application. Knives that require extreme control, like scalpels and wood carving knives, have most of their weight in the handle to allow precise application of the blade.
General purpose knives typically do well with a neutral balance right near the index finger. This allows the user to feel the heft of the knife and make use of the entire length of the blade while still maintaining a high degree of control.
Blade-heavy knives are typically choppers. They have a weight-forward balance that allows them to be swung with greater momentum and power.
As for throwers, I am always amused to hear that a knife is "perfectly balanced for throwing." In general, there are three possible types of balance: handle heavy, blade heavy, and center balanced. There are throwing techniques for all three. As such, "perfectly balanced for throwing" isn't all that special a qualification.
The basic rule is that you grip the light end of the weapon and swing the heavy end when you throw. Center-balanced knives can be thrown by either the blade or the handle. If you'd like to learn more about this, here's a link to a clip from the segment I did for the Discovery Channel's "Time Warp" show:
http://dsc.discovery.com/videos/time-wa ... ysics.html
Can you throw a Spydie? You bet! I've been throwing Delicas and Enduras for years--typically by the handle with a vertical orientation for a no-spin or single-spin throw. They also throw by the blade with a "sportsman's grip" for half spins.