The white lines was a bug in CS6. I reported it, and I believe it's fixed in CC. the pattern maker in IA is much better than what you can do in PS. The new Deco Scripts add a lot of flexibility. With the latest release of CC 14.2 a user interface has been added to the Deco Scripts, making it a bit easier to get an idea of what you're doing. For CS6, I wrote a script that creates a UI, but there is no feedback window. It does allow you to adjust all the scripts variables without having to edit the Deco script code. You can try it by downloading it here:
You will still have the white line issue unless you upgrade to CC.
So would I have to sign up for Adobe Photoshop CC and pay the monthly fee then?
To use the new features such as the built-in UI and the preview window, yes, you would have to subscribe. To use my script for the UI, then no, you can use CS6, but the issue with the white lines will still be there, unless Adobe put out a bug patch on that.