Tom,
I would agree with that too.
Noticed a BIG difference towing a 6x8 utility trailer going from a 3.5 to 5' tongue. Especially with the longer WB trucks I've had. As the trailer turning radius got larger, to closer match the trucks radius. On the other hand, towing with a 6' box short WB S10, or a Nissan pickup I had, those could out turn the trailer backing, so not as big of a deal with those truck. It still became easier to back. Just not as noticeable.
The 5' distance also helped with my flat bed trucks, as I could also then jack knife the two utility trailers with those trucks vs only getting to 60-70 degrees off center.
I had toyed with extending the hitch a bit on my TT, never got around to doing it. 6" would have been nice to have, a foot better yet.
I also noticed less sway issues with the two trailers that had the hitch extended, as more wt was transferred to the hitch with equal placed loads, in these two trailers cases, typically lawn mowers and other yard maintenance tools and equipment.
On opposite option, ie extending the hitch bar, this usually makes it harder to back to the trailer too.....an inch, one may not notice, a foot or more, you will notice this.
Marty