Checking frustrum against Bounds per Object VS Player&List?

If you're trying to do visibility testing, you can just use renderer.isVisible. http://docs.unity3d.com/Documentation/ScriptReference/Renderer-isVisible.html

(Note that this will return true if it is visible in the scene view)

Are you disabling the renderer for performance reasons? You shouldn't have to do that, Unity will automatically cull it.

In that case, I think you would be better off iterating through a list rather than attaching a MonoBehaviour to each object. As long as you aren't using something expensive to generate the list, I believe it should be slightly faster.

Renderers also support OnBecameVisible() and OnBecameInvisible() messages. They'll only be called if the renderer is active, but your scripts will get the message whether they're enabled or not.

If you're really set on calculating this yourself, I would just try both methods and see (empirically!) if there's a significant performance difference. If not, just do whatever's easier to maintain.