Class B's are no more or less durable than any other RV. As a matter of fact, because of it's smaller size, you would probably have the advantage of better fuel mileage & would definitely have better maneuverability due to the shorter length. You'd still have all the creature comforts (heater, stove, sink, bathroom, dinette convertable to a bed) of any RV. As is the case with a lot of items, smaller can cost more, but if you can go used, you can save a bunch of money.
BTW, I see this is your 1st post.