WDH or sway bar

got the 600lbs rated one. 

I got the 400/4000# Equal-i-zer because I will never buy another RV.

I was looking at the 400/4000 but they didn't have it in stock and I was there. So the 600/6000 was the next choice 

Originally posted by Hairy Podders We went with the 500/5000 Blue Ox per the dealers recommendation.

I'm always puzzled by the recommendations of a sway bar no matter what.
I currently have in my yard 8 trailers, I kid you not.  I have owned probably 20 or more in my life and have NEVER had sway with a properly loaded trailer.  Period.
The only time I had bad sway problems was with my 10,000 lb capacity dump trailer.   Picked up a load of crushed stone and the loader operator dropped it a little too far back.   A 10,000 lb load of crushed stone isn't a very big pile, a full load to the brim in the trailer, 12x6x2 would far overload it.
 Stopped at the nearest hardware store, bought a shovel and spent a very unpleasant half hour in summer heat shoveling stone forward.  Sway gone.
That rig weighs in at 23,100 lbs leaving the quarry, 10,000 is the truck the dump trailer is 3100 and the load 10,000.
Even a 10,000 lb truck does not stop sway, proper loading does.