I have to agree with Kajtek1, My old 30ft TT would make my srw F250 wiggle quite a bit when big trucks would pass me. It barely moves my dually. (no WD hitch on either)
Some will argue the point about not needing a dually, but common sence will tell you that 4 tires are more stable than 2 simple as that.
Not trying to stir the pot, just relaying what I have learned by towing with both.
I was dead against a dually when I found mine, but the price was right, and now that I have felt the difference myself, I will never go back to srw as long as I have a trailer to pull.
The peace of mind (and lower blood pressure) I get from the dually far outweighs the cost of two tires.
However, bank/food drive thrus are a thing of the past.....just sayin!