I sit but try to get up often as it kills my back, then my leg or knee will hurt. I have thought of standing more and do when I pin, cut, press and fill bobbins for quilting. It is a bit different and would be something to get use to.
I think this would be a good subject. If it doesn't work they don't have to do it.

I have lower back pain from a torn lumbar disc and like to do many tasks standing up because sitting long periods of time is sure to make me hurt. I've tried sewing while standing up, but after a few minutes my hip starts hurting on the opposite side that I use the foot pedal. I know from past experience it's because it's throwing my pelvis off level to have one foot lifted and pressing down on the foot pedal. I probably need to work for awhile with the other foot on a book to bring them both at the same level to find out if that would help. For now, I do everything else in sewing while standing and work on about 36" high tabletops or counters.

An interesting subject. If I remember I will ask my Physical Therapist which is better for your back. Personally one reason I am not even interested in a long arm is because to me it would be like standing at machine in a factory. My lower back gives me a fit if I just stand for a few minutes.

I have a LA so obviously I DO stand and quilt. But...for the rest of my sewing and cutting, I sit. I have my ironing board at a comfortable height, and that is usually where I do my cutting and ironing. I have had two back surgeries and have had back pain requiring heavy duty pain meds at times...(makes for some interesting quilts)...LOL, of COURSE you know I'm teasing, don't you? Well, don't you? Actually, if I'm hurting so badly I have to resort to pain meds, I just don't quilt until I feel better. But standing is a very doable option for me...

I worked for the seat supplier for the automotive market. The companies that sewed the covers for the seats had everything set up for stand up sewing. It was very popular to do ergonomics on all aspects of manufacturing back then. I suppose it still is. But the sewing was done in the standing position, FYI.

Just a personal observation here, but any time I do an activity that requires standing in a fairly stationary position for any length of time causes some degree of back pain. Don't know if it is posture, repetitive motion or what. Sitting on a tall stool works better for me than standing in most instances.

very interesting subject ergonomics. First IMO, which may not be of any help, I think you have to consider your body. If you don't have any issues with your body and you don't want one, you have to find the correct position to have your body at it's correct posture. And that may not be the proper way to say it, but you know the WII game where you stand and it tells you if you are properly in balance, well I guess that's what I mean, you have to properly have your body in line and balance no mater if it's standing or sitting. According to research, our bones and vertebrates start to loose many factors. Mine unfortunately lost many due to wear and tare. But standing puts less pressure on my back then sitting, however, any professional will tell you that when you are doing repeative motions in one position

(sorry pressed wrong key) your body will cramp. The best advise is to make sure your spine is always straight to have less pressure on it, and the working arms need to be at a 90 degree angel. For people who have back issue's like me, it is recommended to wear a good back brace to keep the lower back in correct position.

I use a mixture. Cut and iron standing up. Sew siting . On my long arm I stand but sometimes due to physical problems I have a kitchen stool to sit on not on wheels. Which works very well.
I like to keep moving position and stretching and wiggling my spine legs etc.