BODS replacement with SAP BW UD ,DB and OpenHub connections

Hi Experts,

Environment : SAP BW ,Oracle ,SQL Server , BODS 4.2

we are planning to install BODS 4.2 with IPS for extracting data from different legacy systems and load to BW and send data to different legacy systems from BW.

Now we are using UD connection and  in BW to do the process .

Please provide the following details.

1. Advantage of using DS over UD ,DB and OpenHub connections.
2. High level architecture of how the DS will connect to Oracle and SQL Server .

Thanks in advance.