Bas, your assumption and assertion/conclusion is incorrect on several points.
Merely saying something to telling something to someone does not REQUIRE that the person have experience (i.e. "knowledge") of the thing itself.
I could tell you that Jamaican Gold you have been smoking there in the Netherlands will "open your mind" but that doesn't mean that I have actual experience with it.
As it turns out, Satan did have personal "knowledge" of good and bad things, being at first a righteous angel and then out of choice becoming something bad, the opposer to God. (Jehovah God is perfectly good and has not known "evil" so your conclusion that the Devil = God is off.)
But you are missing the whole point about what Satan was saying. The issue is not that he was talking about either the "capacity" to make moral choices nor experience of both good and bad things in life. Adam/Eve already had such capacity to make moral choices, such being both the nature of man and evidence by God's placing before them the trees of life and the tree of knowledge of good and bad from which they were told not to eat. Additonally, even in Paradise or as they expanded they would have experienced "bad" things, a stubbed toe, a prickly thorn, hunger/thirsty pains (that would have been quenched when they ate or drank), fatigue, etc. They were fully human after all.
Anyway, the point is not these things but rather the issue was one of sovereignty, that is does Man have the "right" to define what will be the moral choices. Such "rule setting" belongs to the province of God. Thus Satan's lie was that man could be "like God" that is be equal to God in having the right to define morality and by extension to live and be ruled without Him.
-Eduardo