Even with a 6MT I might want to at least try it dialed back just a bit from time to time. I can see where this would be nice when you're in stop and go driving, driving in the rain, etc. As Shiv said, maybe setup alternate maps.
Actually, I'd feel alot better about the wifey driving the car in the rain with the ability to reduce throttle response. It's way too easy to break the tires loose in nearly any gear in the wet!