Hi Joe,
When you look at the source code here:
https://github.com/SAP/openui5/blob/master/src/sap.ui.commons/src/sap/ui/commons/Menu.js
(or via debugging ;-), you can see that it uses sap.ui.unified.Menu now. So they are same.
For this particular commons.MenuButton (see also discussion in http://scn.sap.com/thread/3240903 ) there is no equivalent in unified.
the Demokit shows now
that you can just use a normal Button and use the press event as expected. So you should be able to create your menu when using the press event,
best regards, Sophie.