Toyo Open Country AT2 - MPG vs Stock for '1/2 ton' owners

I updated the title to clarify I am looking at the AT2 which is a pretty modest AT tread. They have a good reputation as general purpose truck tire and are supposed to run pretty quiet.

As for weight the Toyo is within a couple pounds of my stock tires. These are all E rated (I run the max payload version of the F150).

Rolling resistance and impact on mpg is not obvious so that is why I am asking for some 'real world' experience.

Thanks,
Stu