Cancelled my order for the Planar and ordered...
Dell S2340T 23" Multi-Touch Monitor
I plan to use this as a family toy, sharing it around the various house computers and family members. Some more expensive screens can work alone running Android on the home wifi to watch movies and browse the web (not connected to any house computer). You can then wire them up to a PC when you want.
Also, some touch screens aren't great in the corners, and if you use Windows 8, you know that there are important things in the corners. So, to have generic fun in Windows 8, you want the slide from the right, top and left edges of the screen to work smoothly so you can open and close apps dexterously.
I'm not sure how much this matters from a Sonar point of view. I suppose it would be important to be able to open and close the inspector and the browser (both at the edges of the screen) with a touch. To a large degree, you could have a lot of Sonar Touch fun without using the edges much.
If you can get along without the edges though, the price of touch screens comes down a couple of hundred dollars. From what I read of the Planar Monitors from people who used them with Win 8, they do work but they caused a lot of general frustration for people who didn't have a specific app they wanted touch for.
I'm guessing the bakers have more breadth of experience than any of us. Bakers? Are you working with multiple touch monitors? Does it work well? What are your lessons learned with monitor choice?