I use the Alias Map as MY map. The Object Map is TestCompletes map.
For me, the Alias map makes most sense when you can relate it directly to what you see on your site/application.
But sometimes, the way an application/site is built, makes it hard to generate an Alias map which accurately reflects what the user sees. (Clever uses/combinations of tabs/frames/embedded panels are the usual culprits)
To get round this, I use multiple copies of certain items (see my link above) to give me a logical representation. There are times this is awkward or just not possible depending on the application.
The ability to create dummy objects to give your Alias map a more logical representation of what you see would be very handy here.