I know about QL and its default value for start pressure...same for GRT. Those are just SWAG values, in reality (but you gotta have something). If we really knew all these values we could probably make the program work really well.
I see NO field for primer choice in GRT. I also checked for updates and I have the latest version of GRT.
And YES, I understand that start pressure will be affected by numerous things including the primer used. That's a given. To quantify start pressure with any precision is a different story.