Good grief! I would hope that "Forgive us as we have forgiven" isn't correct theology! I don't know about you, but I want to be forgiven FAR MORE PERFECTLY than I have forgiven others!
The norm is I will forgive but I won't/can't forget. God says "your sins are forgiven and I will remember them no more". I think I wan't His kind of forgiving, not mine.
Or it could be that forgiveness is like love, you can only realize it in measure of how you have given it.