I'm nearly always at my computer by 8:30 in the morning, and don't leave until perhaps 8:00 in the evening, although I usually don't stay seated for more than 10 minutes at a stretch. Because I'm using an audio transcribing set up I'm always using my left foot for the playback pedal, so nearly all my weight is on the saddle. I considered the saddle chair because I found that riding my BMW I was practically pain-free because of the seat design.
I won't go so far as to say that the saddle seat has "fixed" my back problem, but it's certainly been a while since the back has given me any trouble.
Because of the amount of adjustability in the whole set up, any discomfort can rectified very easily and quickly, but I stress that I am seldom seated for more than 10 minutes at a time, whether I'm in the saddle, or in my standard typing chair.
Without wanting to get too technical, the human spine has a set of natural curves which the position in the saddle seems to replicate or work with.
Personally, I'm quite comfortable with the saddle, but each individual must make their own decisions.