I'm not sure exactly what Sable is referring to, but apparently I was not clear with what I wrote, or I was referring to something specific, or I've just forgotten something. After over 20 years of writing about this stuff, there's a high probability of the latter...
There was a time when we were having a hell of a time with tin consistency, which is one of the reasons we moved to the current flat tins. (I'm terrible with dates, but I think it was about 2005-6 when we made the change - certainly before 2007.) Even with the older tins, it was only a couple of batches from ca. 2001, as I recall, that had serious issues. Since switching, I've been more than satisfied with the quality of these tins. They have been extremely reliable, both with holding their seal, and with plastic over-caps that actually fit. (THAT, too, was a recurring nightmare with the old ones. For some reason, the manufacturer of the original tins and maker of the plastic over-caps could not always agree on what 2-11/16" was, and the caps ranged from being impossible to put on to impossible to keep on. Must have had different rulers.) I have no problems at all recommending aging my blends in the tins at this point, and that's exactly what I do.
What I have had many problems with over the years is flat tins, especially the rectangular ones. While some have held their seals brilliantly, others have not. As the sealing compound dries over time, the absence of a solid mechanical crimp, such as on pull-top tins, can result in the seal being broken by the slightest knock, or even a sudden temperature fluctuations. The flat, round tins with the "semi-threaded" lids have fared better, but haven't been perfect. I know a few pipesters who routinely seal their flat tins in vacuum-bags to help guard against this. Seems to work.
I have always advocated, and still do, putting tobacco in jars once you've opened it, unless you're going to smoke through it within a month or two; though the current plastic caps do a pretty good job, they're not perfect, and for longer term storage, jars are best.
Did I miss anything?