There are many different chemistries (alloys) and heat treatments of aluminum (and steel) and it is impossible to say that aluminum that is 1.4x the thickness of steel will be equal in dent resistance and have it apply to all types of aluminum and steel. Some alloys will be better and some will be worse. From what I have seen, the body panels on MS are significantly thicker than typical steel panels (if I have some time, maybe I'll measure them with an ultrasound) and appear to be significantly stiffer than typical steel panels.
Also, so, my wife got rear ended in our Land Rover (which has an all aluminum body) a few years ago by a Chevy pickup and all the Rover needed was a new bumper, where the pickup was severely destroyed, lost all it's fluids and was undriveable. You could see where the aluminum body panels had been bowed far enough to come debonded at a seam, but completely returned back to the original shape on its own. They just had to glue it back together. I am a big fan of aluminum body panels. I also happen to be a pilot and own a aircraft service center and have a lot of experience with aluminum structures.
Lastly, a paintless dent removal tech told me that aluminum panels on cars are much easier to fix than steel. Not necessarily the same on airplanes that have a much different alloy than cars use.