Will I regret change to 3.55s from 2.76s

Absolutely. How many dudes drive these cars as daily commuter cars?
I used to drive as much as 1000 miles a week to some out of town jobs. I drove a 2007 Dodge truck that got 16-17 on the freeway. I was fine with that.
However....One advantage with improved gas mileage is that it allows you more range between gas station stops. If you just drive the car around your town, go for what makes it the most fun, whatever your definition of FUN is.