When I used them on my stock cherokee the fuel mileage was about average. They did great on dry roads, wet roads and snow. A great tire all around.
As for wear ... I only ran them for about 10K miles before I switched them out for mud tires - not sure how many miles are on them now. Probably closer to 15K.
They are wearing well, except for two that wore on the outside from the jeep being out of alignment.
A cousin of mine had Vatiivas on his truck and got 60K out of them.