Hi Venkat,
Two DSO's and self loop transformations may won't be needed.
please you can design data flow like below and test at dev system for delta loads.
Data source---->DSO-->cube
source to Data source - Load Full load info pack
PSA to DSO - Load full load DTP
DSO to Cube--Load delta dtp.
DSO - its overwrite function. So data deletion is not required.
DSO overwrite functionality works based on key fields which we used at dso deign layer.
form DSO changlog table we can load delta data to cube.
Thanks