I'm not trying to steer you away from D8Bridge, but if you haven't chosen a DAW software yet, the current release of Cakewalk Sonar X3 fully implements its user interface through touchscreen (multi-touch gestures) in Windows 8.x -
http://www.cakewalk.com/Products/SONAR/touch.aspxThis means you don't need another software to go between your touchscreen and your DAW. There may be other touchscreen DAWs out there now but Cakewalk have been at it since X1, so a few years now.
Marc's D8Bridge v2.0 isn't on the market yet, and only he can tell you what he has in mind, but I believe the d8b surface will be graphically rendered and the graphics will respond to user input (mouse?) to send MIDI messages to the DAW. I don't know if touchscreen is in his plans or not; he'll have to let us know. This D8Bridge GUI will likely be a less robust interface than hands-on the DAW GUI itself via touchscreen, that is, the DAW touchscreen will permit you to interface with any element of the DAW GUI whereas the D8Bridge GUI will likely be confined to the normal controls found on the d8b surface (I'm guessing). The strength of the D8Bridge product, in my mind, is the tactile feedback of having your hands on a fader or a knob without having to devote any of your attention to a screen or visual elements. Perhaps the ideal environment is a combination of both touchscreen (like the Cakewalk X3 DAW GUI) and tactile environment (like D8Bridge).
Maybe Marc can elaborate for us. Hope this helps.