I have for about 15 years used a stool to sit on at work, rather than a desk chair that I can slump in. I have found I feel much better - the stool forces my upper body to be actively held up and balanced; also, when I do go to meetings, instead of being annoyed at sitting in some dumb conference room, I am a little happy to be able to slump like a normal slouch.

I put a zafu (kapok filled, and not too full so its soft/adjustable) on the stool, and adjust the desk height so I don't have to reach up at all to touch the keyboard.

I also do a lot of zazen on a zafu (with legs crossed) so keeping my torso upright is pretty ingrained into my body.

This is just anecdata, but my dad suffered with back pain his entire life (included multiple herniated spinal disks), knock wood, I haven't. If I skip the check on the keyboard height and find I am reaching up for a while, I will get shoulder soreness, but so far early enough to function as a warning to lower it.

Sitting upright as tho you are a world honored one does I think affect the entire mind/body system in a healthy way :)

Spot on. I used to have back pain and all sorts of discomfort throughout body, neck shoulders, etc. until I figured out how to properly sit. Luckily I haven't had any issues lately, I'm in my mid 40s and have been in a much better shape than I was in my mid 20s. I don't use a stool necessarily but I try not to use the back support too much and for me the sitting area must be rigid, any cushion can mess up with my sitting position.

Bingo. As they say, “motion is lotion.” Staying in any position for a long time (even a “good” posture) is going to cause problems. Better being active if you’re passive, resting if you’re active, moving around, taking breaks, and basically just switching it up. All more important than doing one static pose or repetitive motion for an entire day.