Is the "righteousness of God" more than a life of perfect submission?

Many reformed protestants believe in "double imputation" - the idea that our sin is imputed to Christ, and his righteousness is imputed to us. 2 Corinthians 5 is often the source quoted for this: >God made him who had no sin to be sin for us, so that in him we might become the righteousness of God. **2 Corinthains 5:21 (NIV)** The way this has often been explained to me is that we are not able to live a life perfectly obeying God, but Jesus did, and so his life counts for us. But is this all Jesus' righteousness is - the same as if we (theoretically) we to live a life in perfect submission? Or is it correct to say that even if we were to live a perfect life, the "righteousness of God" would still be greater than the righteousness we had achieved? I'm aware that this is an area of theology I struggle with, so perhaps this question doesn't make sense to people more learned than me. But do any of the greater Reformers, or other notable writers, comment on this comparison? *Note that I am specifically asking about those who believe we are imputed with the righteousness of Christ, as opposed to those who understand this verse differently.*