A lot of heavier guys get plenty of use out of freewheel hubs.
According to Jobst Brandt, freewheel axles bend and fail because of metal fatigue, so they'll be good for a while, then they'll go bad.
Replace every year or so and it will be as good as a freehub unless you hit a lot of bumps or are very heavy or powerful.
I personally believe that it is utterly critical to keep the cones adjusted to zero slack but have not found any corroboration from anyone in the know that a poor adjustment can cause bending.