The durability part is hard to answer not knowing the driving conditions you put the motor under. The motor would last as long or longer than the factory 4.0 in most vehicles. My TJ 4.0 has 250,000 miles we rebuilt my daughters 4.0 at 189,000. The stroker motor having more power you don't need to work it as hard as the stock. I have guy's that are getting within 1 mpg as the worn out stock motor. If you are in hilly terrain you may gain mileage. Not knowing a lot about your Jeep if it has bigger tires,gears changed, it is a little hard to give you all the answers you are looking for.
Thanks