Anyway, I've been playing with it standalone for a while and finally today in combination with instruments (brought their own surprises, like you'd expect) and I think I've got things mapped out now more generally. It's going to be a difficult habit (or really, set of habits) - to break. But it's worth it. I mean, I'm not turning into Ella Fitzgerald or something suddenly, but the thing I hear in recordings as a weird brittleness/confined tone that drives me a little bit crazy pretty much go away when stop doing these little things I've been doing since more or less forever, and I want that better sound kind of a lot.
Weird set of habits tho'. I wonder how I got into them? I wonder whether the airflow-in-sinuses thing is related to my grass pollen allergies; that'd make a kind of sense.