I have a XM818 I bought in 2009 with 147 miles and new NDCCs. It now has over 4800 miles and I had to replace the front tires around 4000 miles due to wear and cupping. The rear tires still have about 2/3-3/4 of the tread left. All of the miles are highway, and most are with a load.
I have a M931 with G177s used in the same manner that has a similar tire wear pattern. The front tires wear quickly and cupping is an issue. The rear tires have minimal wear. I don't have as good of a data record as with the XM818, but my impression is the G177s have only a slight advantage in tire wear.
If I rotated the tires in both trucks as per the TM, I should be able to get 10-20K miles out of a set of tires. However, the tires would probably would probably be too weathered due to age before they wore out