Regardless of manufacturer claims there are always some conditions that will cause a tow bar to bind. Those conditions might include attempting to disconnect when the toad is at an extreme angle to the motorhome, the toad significantly higher or lower than the motorhome, or at an extreme side to side angle from the motorhome.
That being said the non binding bars do a much better job than those that don't have that feature. The non binding feature is simply a difference in the angle that the locking caams lock into the extension rods. The non binding ones have a sloped angle on the cam and a taperd slot in the bars. The standard versions have a more square cut cam and square cut slot in the bars.
Our first tow bar was a Roadmater Sterling. It was not a non binding design, but if the toad was relatively in line with the motorhome it would work fine. It was destroyed in an accident and replaced with a Roadmaster Sterling All Terrain, which is a non binding tow bar. This one is slightly more forgiving in that the toad doesn't have to be nearly as well aligned to the motorhome for it to work properly. We used the previous bar for 110,000 miles with no problems. We have about 35,000 miles on the new one, again with no problems.