Let me first mention that I'm new to this but am familiar with gearing ratios in relation to motorbikes so it's not an alien concept.
Let me also qualify my statement in that I am quite fit, do a lot of exercise including spin class and used to run quite fast. I like pushing the big ring, and my route to work is mostly flat or slightly downhill. I wore out the 11tooth cog of my previous cassette, and only that cog- so my reason for going up on the crank was to prolong my cassette life more than anything. My timing is also based on strava which has innaccuracies, but is generally consistent over a known route.
It's difficult to quantify until I next do late shift for a direct comparison with traffic light phasing and traffic density, but I've gone from 16 mph avg to 17mph, literally overnight with no other changes. That's 1mph avg over 15.3 miles.
If you want to see the data I'm on strava. I list when I make changes, day of the week and shift i'm on so I can compare scientifically ish!! The close ratio rear certainly helps with acceleration btw!!