Without reading all of the post before this one, thought I would share and hope its not a repeat.
During recent 1900 mile r/t from MD to FL back to MD..had the opportunity to observe a few trucks with "super singles". What I noticed it they appear to have a little more "tail wag" and move a little more when being passed or passing other big vehicles. They also tended to "crab" (go down the road at a slight angle from front to back) a little when the truck moved from side to side in its lane.
Only saw three that I remember and closely followed two..one for about the whole state of NC.
Just a small observance in both time and distance, but it was noticeable, even if just a little.