Brendon,
It is quite true that a hub with screw on freewheel is more prone to bent axles than a freehub/cassette setup because of the way they are designed. On a freewheel hub the driveside bearing is set in close to the center of the axle, leaving quite a bit of unsupported axle extending out to the dropout. On a freehub the drive side bearing is out closer to the dropout so the axle has better support.
Regards,
Raymond