Thanks for your response.
This is what I understand:
1) Branch office SRX can use " revenue port" i.e the port is used by transit traffic to source SYSLOG since this port exists in data plane .
Same recommendation is made for high end SRX to use revenue port to source syslog rather than using managemnet port.
My question is: If we use MGMT port to source syslog rather than Revenue port on Branch SRX such as 650 , does it not have any impact on control plane versus when using Revenue port?