AC8.1 improves Composites substantially. A summary.
You can now control the linetype, pen, and visibility of the lines between the composite skins, independent of the fill pen.
Composite Skin and Separator Lines
Each separator line can be selected and edited, just like each skin fill. You can even choose to hide the separator line entirely.
Separator Line Settings
This means you can have a composite of stud wall and masonry veneer, and show the masonry hatch while hiding the drywall line.
Mmm...Control...
Currently the only way to use the 'hide' option is to set it in the composite. Unlike the other pen and fill settings, there is no way to use the wall settings. In order to hide the separator line, you must check 'Composite's Separator Lines' box in the wall settings. You must also check this box if you want the separator lines to be visible, but differ from one another. Feel free to use the composite's settings for all the pens and fills; just make sure you set the composites right. The templates are good to go.
It is now standard (quick, huh?) for stud wall composites to hide the separator lines. Change your existing walls accordingly.
The white lines don't exist, including that annoying crossing one.