Russ:
Whether Dragon tells its sales-force or reps "we did" or "did not" ever change the DS formula is pretty much besides the point. Having "problems with some batches" has exactly the same outcome as doing an official change-in-formula, when it comes to chemistry. It creates chemical variation among batches. And chemical variation leads to variation in product performance.
And the "performance" of DS plastic is affected by interactions between samples of DS (track-sets, other DS parts) and their immediate surrounding chemical and physical conditions - their ENVIRONMENT. Temp, air-quality and composition, radiation, contact with other substances and materials - these compose the environment, and these affect how much and how fast the DS sample degrades and decomposes.
So what we modelers get from all of this is what amounts to a matrix of possible amounts of degradation over some period of time. Each kit provides a sample of DS. Some are surely pretty much "exactly" the same as some others (all came from some one batch) - these will all probably react about the same way to the same set of chemical and physical conditions - the "exact" same environment. Every OTHER batch is chemically DIFFERENT. And it will react DIFFERENTLY to some or all of those environmental conditions.
Because NOBODY actually KNOWS which exact batch with what exact actual formula they get in each kit, NOBODY has any way of actually EFFECTIVELY PREDICTING what will happen to their DS tracks! All you can do is GUESS and HOPE.
And NO, I wouldn't begin to buy that Dragon has actually IDENTIFIED exactly what the chemical problem(s) are, beyond finding that some batch(es) appear to have excess amounts of one ingredient or another. How could they do that? They can try to "clean up" their chemistry (meaning better QC and less variation in batches and between batches of DS), but even if they attained a "perfect" QC and all batches came out "exactly the same"... This still doesn't solve any problems for modelers! NOBODY KNOWS what actual combination of environmental factors will apply to every kit! (And rest assured, all kits are NOT handled "equally".)
IF everyone stored and handled their DS from these hypothetical "exactly the same" batches in "exactly" the same way (same air chem, same temp regimes, same air-pressure, same electro-magnetic radiation exposure, etc.), one could predict that "all" of those DS samples (track sets) would last equally long and degrade in the same way at the same rate. Right! GOOD LUCK with that!
It doesn't matter what Dragon says about its DS chemistry. People don't all handle their DS exactly the same way, and D's DS batches aren't actually all "exactly" the same... So what will happen with your sample of DS is pretty unpredictable. It MAY last a long time! Or it may melt down tomorrow.
And that is what we are seeing across the many reports here and elsewhere concerning people's experiences with DS.
Cheers! Bob