Limitations is a difficult thing to describe. it's not designed to be an "anything you want" solution. there are some limitations with the custom analysis reports when you try to add too much data, or data from different subject areas.
If this is a Simphony standard solution then they are limited to the 3 custom exports ran 3 times per day, with costs for each export. For premium its a cost per custom export. There are standard exports available (no Cost) that are run once per day and EOW.
information on the standard exports can be found on docs.oracle.com
the RA 9.0 dashboards and all data inside RA is near real time data. as long as the site is connected to the internet and the data center the data is posted generally within seconds and available in RA, this also goes for the inmotion mobile application. the dashboards are capable of handling historical data as well as "today". depending on the particular dashboard there may be limitations on the view selected and how the data is presented in real time. i.e. day part breakfast vs lunch at 11:30am would have complete data for breakfast and partial data for lunch. But, both sets of data could change if items are refunded or altered later in the day.