Chris--my wife just bought a pair of those (thanks to your recommendation
) and says her back hasn't felt this good in months.
As to the standing/sitting discussion, I'm in the standing camp. And I generally tilt the work slightly toward me for the reasons Rich gives. Also, it's important to set the work at eye level to avoid the distortion one gets with having it too high or low--bifocals can confound that sometimes, though.