Here is some good info.
https://www.bicyclerollingresistance...thon-plus-2015
from the articleAs expected, rolling resistance of the Marathon Plus is higher than the plain Marathon. Depending on air pressure, you're giving up 4 - 6 watts of power per tire (20%). This isn't all that much given the 2 mm of extra puncture protection the Plus provides. I think it comes down to personal preference whether you like the lower rolling resistance or the higher puncture protection.
When we compare the Marathon tires to similar tires from different brands, the Schwalbe tires seem to be in another league when you take both puncture and rolling resistance into consideration. At least at the time of this writing, the other brands just can't compete.