Can you please give more information about your Project:
- What are the capacity Planning.
-How many users are accessing?
-How big is going to be PS and SP on Data wise.
I prefer to put the PS and SP as separate Installation on different server. (easy for upgrades and patches)
If the Data are not going to too big i kept on same server with different instances using sql alias. keeping separate Drives for Data and Log Files.
At the end everything is based on how much data they have in current environment and how much growth they are expecting.