I'm not sure that concept of swung quarters can be isolated on it's own. I think it'll always need to be viewed within the context of the music that it's supposed to support.
Sometimes the "spang-a-lang" is a very wide triplet feel with a lazy, skipping sensation to it, sometimes it's right there with the triplet and sometimes it gets pushed into the sixteenth note realm (like it's notated in the Chapin book). Plenty of drummers play with that concept...during a pushing shuffle part of the music they might ever so slightly go into that sixteenth realm, while they might otherwise play it straight up the middle or even lay back a tad with the skip note.
I think the concept really means that one could try to convey those different feels just through the quarter note...and yes that'll probably mean being very particular about it's placement and sound....do I want to push and excite the whole thing...or do I want to convey a relaxed time feel to the listener... The way you strike the cymbal...this one I can't really explain, but I know there's a difference for me.
I've been thinking about it quite a bit since that thread and I've come to realise I use that whole quarter note ride thing a lot more than I thought. And mostly for effect...for pushing everything when a new soloist starts or when we transition from the theme into the solos...for laying back when it's a softer section...during bass solos etc... Just playing quarter notes on the ride can be a real eye catcher in a jazz context....everyone kinda perks up and goes "hey, something's about to happen here...."
But again, I think it needs to be viewed in the context of what's going on around us and then it can make sense to focus on it. What went wrong in the thread, I believe, is that a lot of people equate "the quarter note" to the metronome clicking along....and while it's "right", it's also "wrong". Whatever "feel" you can apply to the eight or sixteenth note can also apply to the quarter note. There's no logical reason to think otherwise in my opinion.