Let’s see, I want to say this diplomatically, so here goes: your argument about using less choke for crossers is interesting, but, well, it has a few holes in it, just like those targets you’re talking about. Pay heed to the mighty Technoid; he has it right as usual. Shot-stringing is definitely confusing, but it definitely has the effect of reducing the pellet density at the plane of the target. Thus, if anything, you should use more choke on crossers, not less.
The choke recommendations in Choke Chooser come from SPRED, which is a 2-D model of shot patterns. This means that shot-stringing is ignored, a simplification that causes no errors on straightaways and only small errors on most other targets. On a very fast, long-range, right-angle crosser, this assumption will cause a modest error, depending upon the quality of your load and barrel, as the Technoid says. The more deformed, slower pellets will arrive at the plane of the target later than the faster ones and, from the viewpoint of the moving target, will tend to miss behind (assuming your lead was right on). Clearly, this effect elongates the pattern in the moving frame of reference, and reduces pellet density in the central part of the pattern. Hence for such a target you should consider using a slightly tighter choke to try to get this pellet density back.
When you talk about a target moving 4 inches during the time it takes a 4-foot shot string to pass, that does not make the target effectively 80% larger. It simply moves a few inches where it gets exposed to a slightly different portion of the pattern. The 2-D model assumes that all the pellets in the 3-D pattern show up at the same time, so the 3-D pattern cannot produce more central pellet density or more chance of hits.
Under certain conditions, shot stringing can be helpful. The elongation of a pattern (in a moving frame of reference) can compensate for small errors in lead and help you break crossers. One situation where this can be helpful is in 12-ga skeet, where there are plenty of pellets and central pattern density stays high despite the shot-stringing effect.
Since these effects are small, the choke recommendations in Choke Chooser are still valid for essentially all crossers and will still give you the best chance of breaking these targets. Sorry Don, opening up your chokes for crossers at any range will do nothing but hurt your score.