Connecting HMI

Hi PLC Specialists,

I am an IT guy who encountered a small issue. Several production lines at our manufacturing facility have Siemens PLCs configured in a way where X1 network port connects to drives, while X2 to HMI. We want to add all the PLCs to a common ethernet network to collect some data.

The electrician suggests to disconnect HMI from X2 port, and add a small ethernet switch connecting port X2, HMI and common ethernet network (re-ip X2 interface and HMI)

I suggest using second ethernet port for X1 interface in the PLC to connect HMI (so PLC would connect to drives and HMI using X1 ethernet interface, and re-IP X2 interface to access common network. To me it looks like cleaner solution. 

Our electrician advises against, but without any reasonable (at least for me) arguments. 

Could you please let me know if my solution (attaching HMI and drives to X1) may cause any issues? I personally think whoever did original design used port X2 for HMI, because it was simply available, after all, there are PLCs with a single ethernet port and still have to work with drives and HMI, but maybe I am wrong?

Thank you!