We recently installed the Action Dashboard solution pack in our development environment. It appears that it does not keep the custom portal homepage by default. I could fix this by modifying DashboardContent.ascx but I didn't see anything regarding this in the doc. Is this the preferred method?
you should edit the config\custom\content\defaultdashboard.html file to change the dashboard content on the "home" tab. However, action dashboard has a bug where this file is no longer referenced by dashboardcontent.ascx. support should be aware, but please submit a bug and we'll get it fixed.
in the meantime, as a workaround, you should be able to revert the dashboardcontent.ascx file from action dashboard to the previous 126.96.36.199 version.