Curious: difference between a WD hitch and Hensley Arrow

Much in the same way a F350 dually would improve your towing performance.
A Hensley would also improve your towing performance.
On a clear sunny day that improvement maybe negligible, on a bad Murphy's law kind of day that improvement maybe invaluable.
Those who own a Hensley are after the ultimate towing performance vs. adequate or very good. Buying a dually is not a pratical solution for most, however many find a Hensley a worthwhile way to obtain ultimate towing performance.