For any who might be interested, I would note this blog post by Rev. Michael Larson in which he describes the difference between the Lutheran approach to the 3 uses of the law (I like that he gives the Latin terminology - the usus civilis, usus elenchticus, and tertius usus legis). He makes excellent points.
Coming from the opposite direction - here is a post on the same distinction from a Reformed point of view
The difference in emphasis is interesting. The Lutheran focus is upon the Gospel of Christ - that Christ Jesus has fulfilled the Law, and that by grace I will do good works. The Law is only needed as I remain in sin, yet as a Christian I will delight in God's Law.
The Reformed focus treats God's Law as a higher reality than the Gospel - indeed, even saying that "The gospel is temporary; the law is everlasting and precisely that which is restored by the gospel."
The reformed end up treating salvation, the Gospel, the Cross as though they were all only some sort of back-up plan, some divine temporary building until we get back to the real thing - God's Law.
This doesn't mesh with the Scriptures -- Christ is the Lamb who was slain from the foundations of the world. Christ's redemption is not just some booby prize that we get to happily ignore in the New Heavens and the New Earth... no, the Lamb who was Slain has begun His Reign -- and even for all eternity Paul will know nothing but Christ and Him Crucified. The Gospel is Central and will always remain.
As for the Law -- it will always remain... but the day is coming when no one will have to instruct or proclaim the law - you won't have to say, "Know the Lord"... because the Lord will have forgiven our sin and remember our sin no more.