Bryan and I were talking about this yesterday and today and it seems, at least initially, that the mechanism driving the issues with sulfur people are having is ultimately yeast choice+Sulfate content. That is backed up at least partially by what Dr. Bamforth said.
Some trends to look for would be the following:
1.) What is the Sulfate content in the water for beers people are having sulfur issues with? Are you adding additional Sulfate on top of source water content and the amount estimated to come from scavenging power of metabisulfite?
2.) What is the metabisulfite dose used in beers where people are having sulfur issues? You need to find the line where you have adequate margin but do not introduce additional Sulfate into the fermenting beer.
3.) Was a yeast with Low to moderate sulfur characteristics used? If so, was that exacerbated by a high dose of metabisulfite or the use of additional Sulfate in the form of gypsum?
Most people who are NOT having sulfur issues are using fairly simple water profiles: Distilled/RO with minimal CaCl and Sulfate driven by metabisulfite dose.
4.) It seems that even in light of the potential for Fenton Reactions and other oxidative precursors, people are having good luck with copper chillers and BTB. That remaining copper in some people's systems may be helping to mitigate the sulfur character as well, with BTB helping to mitigate Fenton Reactions.
Let's also note that people using known sulfur producing yeast that have no copper in their systems are capable of producing beers with only the faintest amount of sulfur, so the issues likely lie in the amount of Metabisulfite used and any additional Sulfate used.
I was hammering away at a point the other day, the "sulfites will all be gone by aeration/fermentation" line of thinking, and while that's technically correct, if Sulfate is the source of people's issues, the amount of the initial metabisulfite dose will ultimately drive the Sulfate contributed up toward the 101 ppm mark. Thanks to Bryan for talking me through that the yesterday.