I am thinking of adding a touch screen to my setup but have read varying reports that the touch implementation in Sonar is not really complete. For example, can notes in the Piano View be manipulated by touch? It seems touch is great for mixing but not all that well implemented for editing. Before taking the plunge, I would appreciate the opinions of those that are using or have used a touch interface.  

Touch is pretty cool but it isn't for everything in sonar.

It is cool for synths, VSTs, playing while you record.

bear in mind, higher resolution on a same sized screen, means smaller images. My laptop (now dead) touch screen is hd but just 15.6", which makes the the icons too small for touch use really. Of course a desktop screen will be much bigger, but bear in mind bot the size and resolution when buying. If the same resolution is available on a larger screen, it may make touch much more useful for you.
 
I've never tried a stylus on a touch screen. I assume they will work, and be better than my thick fingers.