The helpfile states that is boost what that can be done to non-living, non-wordly, clockwork PC's and NPC's. What exactly does it boost, and could people who had experience with the edge put in their two-cents?

Is it worth it or just go with the precision one?

I've never had the edge, but I assume it simply makes your spells more effective against non-sentient NPCs (metal golems, undead, etc.)

The boost, I would imagine, means something along the lines of a spellcraft like bonus where the level of the spells are increased (thus increasing duration and in some cases, the degree of the modifiers like stats), or perhaps they're just easier to land.

If you don't really care much about fighting those kinds of things and are more concerned with PK or fighting sentient mobs, you would definitely want to go with the precision one.

If, for example, I had a sleek barrier wand on an undead mob or fought a lot of necros or something like that, I might consider taking this edge.