Breaking a CV usually occurs as a result of a spinning wheel gaining traction, which transmits too much stress through the system ,and being the weakest link the CV breaks. In your scenario unless the wheels are spinning you wont have a problem, ie you can drive with 1 side on a hard surface and 1 side on soft/ sand etc, the wheels won't be spinning because you have positive drive through the wheel on the hard surface, the wheel on the soft surface will not spin because the diff is locked therfore the wheels will rotate at the same speed.
Where you may have a problem is where both wheels are spinning and 1 suddenly gains traction, ie driving through mud etc. In this case it does not matter wether you have an air locker or and auto locker the result will be the same.
Where you may have a problem is where both wheels are spinning and 1 suddenly gains traction, ie driving through mud etc. In this case it does not matter wether you have an air locker or and auto locker the result will be the same.
