[occamrazor]

Professional pianist practice hours every day. The main differences in posture, compared to an office chair, are:

1. A flat seat, without back

2. No wrist support.

[bbor]

You raise good points, and just showed me what my fallback career should be: Herman Miller salesperson targeting just professional musicians. Proper ergonomics is going to blow their minds! The people who want orchestras to look they did in 1700s Austria will just have to get over it