Hello,
Yes, You can run GUI and CLI at the same time if you have it configured accordingly on the SRX.
As Far as the rating goes i would say it is really good and useful to do the configruation part on the SRX becasue it is pretty user freindly in terms of that. However to troubleshoot any issue CLI is much more easier as it has more felxibility.
Hope this helps
Thanks,
Pulkit Bhandari
Please mark my response as Solution Accepted if it Helps, Kudos are Appreciated too.