Three years out, I'm finding that I actually stand and work for 90% of the tasks I do here at my "station" (I stand as I write this, for example). In terms of how I spend the TIME on task however, it may be a different story. I've never done a systematic study of how I use the station, but I do have some general observations:
I use a diversity of postures, three to be exact:
I can stand, sit at a stool, or sit (or recline!) on the couch right behind me. I have a lectern I made to bring my laptop up to 48" when I'm standing and using the computer. When I get tired, I pull the stool over and rest the laptop directly on the table, which is at 43". I seldom sit for long at the stool though. My back gets stiff after 15 minutes or so, and I return to standing or do something else . I sometimes rest one foot on a low stool under the station, just to relieve my back muscles a bit.
I'm a short-order worker.
Most of my tasks range from a few seconds to a few minutes, and even then, I'm relatively fidgety. (My wife has better sitzfleisch than I, and can sit in front of her laptop for hours.) I seldom stand for more than a few minutes without stepping back to stretch, or walking around the house (a "motor break", or sitting briefly before coming back to the station. I do extended tasks like drawing or Photoshop or keyboarding at the 48" level. When I'm really engaged, I can work more or less continuously at the station for hours. I stand or pace when on conference calls. The station is perfect for other things like wrapping gifts, watercoloring, sorting the mail, or for small repair jobs.
Sitting and reclining are fine too.
I find I do want to SIT on the sofa to read anything longer than a few lines or a page at most. I generally sit for more casual phone calls, book-reading, and the newspaper. On days when I am at home in the PM, I love my naps, and I come back here to read when I find myself wide awake at 3:00 AM.
I cannot imagine going back to work in an office, certainly not a seated one.
Research shows that standing keeps one's metabolism high and is better for cardio fitness than sitting. I believe that. I find I'm more alert and focused (even with my "motor breaks") at the station than at a desk or table, and with 24 square feet of work space, plus all the little pigeonholes and shelves above the desk, I have access to a lot of tools.