Yeah AT is still heavier, and still has slightly more parasitic loss. The main advantage is now in having more ratios for better gear spread, allowing the car to be in a more efficient RPM range more of the time.

6MT vs 6AT version of the same car the MT will definitely win in fuel economy. What's interesting is when we now compare 6MT vs 8AT, or even 9AT or 10AT of the same car.