Hmmm ... interesting opinions. I would only point out that there is a direction toward goodness, and a direction away from it. Sometimes how far in that direction one goes is determined by economics, and by weighing the alternatives. It doesn't change which direction one must choose for goodness, though.
TBP, if we're dueling projects, I've put 20,000 #/hr of raw, boiler steam directly into a 300,000 cfm airstream for an aircraft paint booth. However, that's a process application, with limited long-term exposure to the occupants. Sometimes, they're even on breathing air. Similar to your tobacco example: exposure to isocyanates, toluene, MEK, or worse put direct steam humidification in its proper context.
I've also put in many dozens of Liebert units with direct steam humidifiers, with no clean-steam segregation. Again, that's for a process - with limited occupant exposure (and ventilation) compared to the internal load.
Both of those decisions were economic ones - based on the context of the systems, exposures, and type of occupants in the project. Again, please refer to the subject line, "Steam Humidifiers - Health Care."
It does sound like you are blessed with unusually clean steam, and steel pipe that never rusts. In the deep south where I live, rust appears on anything ferric within a day or two - whether it's used for clean steam or not.
As for SAK9's opinions on the matter, I can't explain them. He doesn't want to use HEPA filtration, either - so what good does it do to argue the merits of clean steam? We each make our own professional judgments. Disagreement is certain to happen.
