stock are strut mounts, not camber plates. they have no adjustment. moving to a camber plate creates a more solid mount for the top of the strut. you get a better road feel and slightly more NVH. a camber plate gives you easy adjustability of your camber if you're gonna mess with it often. i try to keep tabs on my tire wear and fiddle with camber when necessary.
The eccentric camber bolts are alot cheaper and if you're just gonna have a shop set it and forget it, maybe thats the way to go.
the other thing though is caster. basically more = better to some degree. you have no caster adjustablitiy if u just do those camber bolts. to fully correct the geometry on a lowered car, you should really increase caster to keep the car from wandering, as well as to increase camber gain in a turn. (good things) So if you take the plunge on true camber plates, make sure theyre ones that include caster adjustability. That way you get better performance.
All depends on how close to perfection u wanna be.