With my trailer and 3/4 ton, according to the Cat scales and my receiver ratings, I don't need to use w/d. That being said, the only time I don't use it is back and forth to the storage facility (very tight turns at strange elevation angles) when I am totally empty and it is just a few mile drive. I can tell the difference and the unit as a whole feels more stable using w/d.
1998 Jayco Eagle 302FK (Honda EU3000is)
2016 GMC Sierra Denali 3500HD 4x4 Duramax/Allison
2003 Honda Aquatrax F-12X Turbo