I've just gotten the messed up ladder problem again twice in the past couple of days. I noticed it happens when your drag the value so far onto another app's window that it highlights something in that app.
If you are looking to add more monitors to your system you need to use Quadros or video splitting devices such as Matrix Dual/Triple Heads or DataPath X4.
I'm using a couple of dual heads and they work great. I found if you use more than one window you get pretty big performance hit. If you use one window across all the monitors and then have your UI in one part of the window (on one monitor) and then your output on the other part of the window (output monitors) you'll get the best performance. The one downfall of this is that the monitors should all be the same resolution.
Another solution that I use mostly is to use Max for the UI and send OSC to Touch to control parameters. I find this works really well with the least amount of impact on performance. With Max you also have access to the pattrstorage objects which makes creating presets for Touch super easy.