It also seem that you cannot install Acrobat XI along with Acrobat X on one Mac. I recently tried, but was warned, that I have to uninstall Acrobat X before and that the two versions cannot coexist together. Mac OSX 10.7.5.
I also have a Acrobat 9 Pro lisence. Can Acrobat 9 coexist with Acrobat XI?
I cannot see this mentioned in the tech specs:
Tech specs | Adobe Acrobat XI Pro
or in the feature discriptions:
Features, PDF documents | Adobe Acrobat XI Pro
Uwe