Connecting Business Objects in BI 4 to an SAP back-end

I have spent hours looking at the very interesting blogs on what connectivity the new BI4 stack is going to provide. Currently still everything is still under the haze of war while the products are in Ramp Up , nevertheless we can start to form ourself a clear picture of what is coming our way.

In the Current BOXI 3.1 the stack is structured in a way that gives us only a one way to our data.
Report -> Universe with MDX ->(Bex Query) -> (Multi Provider) -> Cubes , with the parts in parenthesis being optional.
It is a stack which can feel limiting when you come from relational databases , but somehow it seems to work when you know how to configure items at each level of the stack. Indeed its complexity comes from the fact that you need every layer of the complete stack to make your reporting project work.
The universe gives us access to predefined filters and a way to catch changes in the underlying regions so as to have stable reports, oh yes and unless you are working with the SAP cube version of efashion turn off database aggregation on measures. No navigation through MDX , this will only kill your performance and give you wrong results. The Bex queries gives you some configuration on hierarchies and currency conversion and some key figure calculations (Measures backend for us BO guys).
the MultiProvider gives you access to parallel processing control over multiple cubes and setting up alternate hierarchies if necessary .
The Cube being the Lowest Level that can be published and the way your information is structured (being your dimensional model) .


In BI 4 (the new name for BOXI 3.1) the reports can be connected in multiple ways to the SAP.
keeping a BOXI 3 like universe over MDX , creating new BI 4 type universe on the infoproviders (multiprovider / cubes / DSOs) , or BICS access to the BEX queries.
Where this is worrying me, is how each stack will have different behaviours and different feature-sets. Maybe even different syntax for each technical stack.
How do the different stacks handle prompts , hierarchies, calculations , ....
Or maybe  will we have one stack as a solution to a problem?
Currently I don't know and we will see how the future will be.