The point is, there are circumstances under which there may be data loss in ways that would not be obvious to the casual user. In many, or even most, situations there will not be a problem, but I'm very wary of blanket assurances that DNG conversion is always lossless.
Yes, there are ways to hose any data during conversion. You had me worried but now I see this is a very
isolated case with one or two cameras with a setting that I wouldn't recommend using for DNG conversion. Unless I'm missing something more. So in the three cases you cited, it's really one. If the end user really knew what we now know, they wouldn't have an issue, they would use a more appropriate conversion setting. With these older cameras set for older software. Adobe should pop an dialog for these rare cases. No excuse for that. I wasn't aware of this so this was useful.