We get many questions like this and we are happy to say that its very easy. Both Pocket Informant and the Agenda products use the Windows Mobile PIM databases for all core data so you will not experience any differences in sync or data representation for core PIM data.
The differences in data lie in our settings and extra data such as category colors, journaling, etc.. You can more easily migrate the category icons in the folders to the Pocket Informant folders in \Application Data\WebIS.
