Iso lines in Silo.
New to version 1.2, Silo allows to view and edit subdivision surfaces using an iso line display mode.  With this new feature, only the edges and vertices that represent corresponding ones on the outer mesh are displayed on the inner mesh.  Moreover, you can effectively select and work with the inner mesh while still retaining the control of the outer mesh.
In previous versions of Silo and in standard subdivision surfaces modeling, you select from the control cage to edit your subdivided model.  Often both the inner mesh and the control cage are shown at the same time, or at other times the control cage is the only part shown while you're editing elements.  Sometimes parts of the control cage can become obscured, and it an be hard to tell what effect your edits will have on the subdivided surface.
Now, Silo allows you to turn off the control cage and make your selections directly from the inner mesh.  Open the Display Options dialog (Options > Display Options).  Unchecking "Show Control Cages" will turn off the control cage display.  If you have "Show Cage Selection" checked, the selected portion of the outer cage will show, but only the selected portion.
Now notice that when you are in face, edge, vertex, or texture selection modes, you can make your selections from the inner mesh itself.  The outer mesh is still there, it's just invisible, though you're still actually selectingthe corresponding elements on the outer mesh.
When you're working in iso line mode, you can do all your standard geometry edits.  Some tools, such as the split tool, will temporarily turn on the control cage display so you can better see what's happening on the control mesh.  For many edits, such as tweaking your shape, it is much easier and more fun to work from the inner mesh's iso lines/faces/vertices with the control cage display turned off.