RFC lookup to PI system or other ERP system.Which is better?

Question

Hello experts,
I have a scenario[RFC>PI(RFCLOOKUP,SOAP LOOKUP)->SOAP] where I have to  fetch or update  the data in the table using RFC lookup in the mapping.
To store or update  the data ,I have created a table in PI system and through RFC LOOKUP I am fetching the data in the message mapping.
                                                                                Some PI developers prefers not to create this elements in the PI system  and suggested a way to create them in the ERP. 
I wanted to crosscheck with you all  whether Lookup to PI system is better or to ERP system in terms of  performance, security and std maintenance.
-Conceptually, they see PI as a communication tool, not the best option for storing data, which is an ERP function.                                                                               
some prefer  ERP option  to Simplify the upgrade / system patching processes. As No Z-Objects makes the checking process much easier and there is no need to adapt those objects to the new release environment.     
I appreciate your valuable suggestions.

Answer 1

Hello Souvik,
Thank you so much for your reply.
But in my case the RFC lookup will be executed twice because the authorization data(token ans sign values which is stored in PI) is valid for 12 hours.
if I find that these data is expired ,I have to do a soap lookup to get these details from a webservice and also have to update the same in the PI table using RFC lookup.All these activities are done in message mapping.
so first RFC LOOKUP is used  to fetch the data and if expired,I get these details from a webservice and update(executing second time RFC LOOKUP) in PI table ,so that next time when request comes ,I will fetch these details from PI table instead from webservice to send message  to the receiver.
same functionality is required for 4-5 scenarios,all acessing the same PI table.
So Kindly advice considering these situation,will the performance,security,maintenance  be good when doing RFC lookup to other ERP instead of doing RFC lookup to PI system .
Kind Regards,
Kubra.