Hi Jobin,
ASC is very limited if you are working with any complex system, You can't extract the whole data model from ASC on a regular basis to an external database. As florent mentioned its not possible to use FDA although you can use flat files in ASC.
Adobe Io is good if you are using ASC data over your website i.e AEM or in Target or in Audience manager.
ASC have really nice capability for reporting(Adobe analytics API's) which is not available to classic users.
@Florent, Do you know any api or tool which we can use to enhance the calender's capabilities in classic version?
Regards,
Amit