Who is using touchscreen in Sonar X3 and with what results?

Touchscreens are good for larger movements, not so much for small, incremental changes.  I have my touchscreen angled in front of me like a mixing board, and it is very comfortable and natural.  But it is merely an option for control, not an all inclusive tool.  Typing, I haven't gotten good at it.  Prefer a real keyboard, even chicklet.  Clicking works pretty good, scrolling and moving (as you would expect). 
 
So, for SONAR I use the touch screen to move around the timeline, expand and contract the timeline, etc.  I'll touch for click to bring up synths effects.  But for the included knobs I'll use the mouse.  And once my hand is there it sticks for a while, until there is a reason to change.  If that pains you, I imagine you'll be back to the touchscreen ASAP.
 
A touchscreen can help, but it doesn't mean not using the mouse.  Or keyboard.  However, if you put it in a good position you can use it for a lot.  And as the software incorporates more touch centric tools, it will only get better. 

  I have mine mounted at an angle like a mixing board also. I have the control bar docked at the bottom of the touch screen. This is probably were I use touch the most.  Also for zooming and navigating. 
  Faders and knobs are a bit finicky. Especially moving multiple faders at one time. 
  Flying out the Pro Channel EQ with a swipe is pretty impressive to onlookers. 
  It's not perfect, but I can't imagine being without it. 

This may be too obvious (sorry) but I assume you use the mouse in an ideal angle. Even the slightest unnecessary bending horizontally or vertically can cause problems. The mouse table must be about on the same level as your elbow when you have your shoulders relaxed. So, arm in a 90 degree angle. 

Unless you buy a larger touchscreen monitor with higher than 1920 X 1080, I can't see getting a lot of use from it.  I have a 23" Acer touchscreen and aside from looking pretty cool to my clients I rarely use the touch part of it.  There just isn't enough real-estate.  Like some, I have the control bar docked at the bottom and the monitor is angled toward me.  It's not prime time.  Maybe a 27" or larger with more resolution would work out.  I'm waiting for the prices to drop on those but it's not happening very fast.

I recommend getting a control surface e.g. the vs-700c which alllows you to control most features of sonar ...
I Have used touch in many ways since it came but was never satisfied ... There is no satisfactory fine adjustment of knobs and faders ... Well it works but using it really wears you out since its hard to get it right where you want to have to slider ...
 
I still it use but only for the following: 

• Start playback in live performances (backing tracks) but even there the play list feature and wireless keyboard are superior
• Arm tracks and push record during song writing session where we have big (!!!) touch screen mounted to studio wall ( but still you do not want to use for much more once tried that)
• Adjust pre-prepared live mixes on my x32 from a tablet ... But even that is less than satisfying because try changing a fader by 0.2 dB ...???

Overall disappointingly little use for the ££££ I have invested

I want to add to the mouse/trackball comments here to say I've recently added a second trackball (Kensington Expert trackball/mouse, whatever they call it).  It's helping a fair bit.  I especially like being able to hold the mouse button down with one hand, while adjusting a control with the other hand (think faders and knobs).  That action (adjusting faders and other controls) plus intense editing are the two actions that hurt my hands the most.  By separating the 'click and hold' from the 'move' actions, it's helped.  And, as you already know, just having the option to use either hand is a bit of a relief.  Since both trackballs are seen as one (I don't install the Kensington software), it isn't possible to switch the left/right buttons on either one without affecting the other, but this hasn't been an issue for me.
 
Also, this is the wrong thread (should be in your other one about control surfaces), but I want to give a shout-out to the Mackie MCU Pro.  Other than a couple of minor display issues (random characters that show in the MCU scribble strips), mine works just fine with Sonar X3e (and all X series).  I like to mix and automate with it, I like using the transport controls, save buttons, buttons for switching between tracks, buses and outputs, and more.  I wouldn't say I use it in a 'deep' way (haven't tried to use it for plugs or sends yet) but for the basics of day to day mixing, I'm very happy with it.  There are others with complaints on the forum about lack of integration or bugs, but that has not been my experience at all.  I use the USB port with mine, Win 7 64bit.

Absynth besides the normal adjustment has a fine adjustment slider. Multi-touch implementation will get better as time goes on. http://www.native-instruments.com/en/products/komplete/synths/absynth-5/ 
the two or three sliders next to each function makes gross or fine adjustment. I love this feature.
 
Windows 10 will have additional functionality for multi-touch. Then I will alos update my computer and get a 32" multi-touch monitor.
 
Part of the reason I use Sonar is ARA for Melodyne and the multi-touch implementation. I recently also purchased FL Studio because again it has considerable multi-touch functionality and can run as a VSTi inside Sonar.