When in normal mode, then typing S, this plugin clears the line and puts the user in insert mode, consistent with behavior described in Vim.

["x]S                   Delete [count] lines [into register x] and start                                                                        
                        insert.  Synonym for "cc" linewise.      

However, at this point, it does not seem to be possible to exit insert mode. The user is forced to hit Enter to get a new prompt. This prompt will actually start in normal mode, which is also unexpected.

I do not observe this behavior when using cc from normal mode. Like S, cc will clear the line's contents and put me in insert mode, however, I am able to hit Esc and get back to normal mode, as expected.