There is no free lunch. The reduction in torque (overall gear multiplication) is exactly the same as the change in RPM. Engine RPM drops by 9%, torque exactly the same, speed in MPH in each gear is up by 10% (what used to be 50 is now 55). That's a pretty big change, and you'll feel the difference.
What you really need is an overdrive to both keep a big 1st gear for traffic, and slow the engine down when cruising.
