I would like to force the overflow icon to always show in the action bar (assuming there are overflow items). On models with a menu button, sometimes the overflow icon doesn't appear and users must tap the devices menu button to get the rest of the action menu items. Users keep complaining about this.
Note that for the context menu, the overflow icon always shows, regardless of whether the device has a built in menu button or not.
I realize that forcing the overflow icon to appear in the action bar would duplicate the functionality of the "physical" one. You might consider that violating Androids design guidelines. In my opinion, though, the users win. They say it's confusing and I believe they're right.