Has Anyone Used One Of These?

The Ergotron WorkFit-S, LCD Laptop Sit-Stand Workstation?  Some of my co-workers are using these so that they can sit and work then stand and work.  While there is no budget at work for more of these in the current year, I might buy one for home.  My hope is that by working standing up for part of the time, I might reduce strain on my arms and burn more calories.  (Treadmill computer desks are a bit too expensive, and I am skeptical that I could work while treadmilling.)