Are you using clone in a negative way? I don't think workflowy has a lock on outlines, One could say that workflowy is just an emacs org mode clone except on the web
checkvist.com is a similar app with great keyboard shortcuts-I use that as opposed to workflowy.
+1 for Checkvist. This tool is so versatile it's unbelievable. I find myself using it for everything, from time tracking to note taking.
Workflowy Pro has custom themes and fonts ;)
And it didn't work ("something went wrong"). Other than that, awesomeness.