I just had an opportunity to test one yesterday against my 210 gold dot dagor. I set up my 8x10 camera to shoot an object at larger than 1-1. I switched the rear element with the front element on the sinar lens, which you are supposed to do going larger than 1-1. It was very easy to work with the Sinar lens because it is 5.6 and once I got the camera in place to focus at that distance I could crank the lens plane in and out and it stayed in focus.
I shot a test at f32 and then put my 210 gold dot dagor on and it was in focus without any adjustment. So I shot the same thing at f32 with the dagor. I processed the film in Rodinal 1-100 and to my surprise the object (a black feather) was quite a bit larger on film with the Sinar lens than it was with the Dagor. The focal length was the same but the maginification was different.
In any case the Sinar lens test was very sharp and it was exactly the same in that regard as the Schneider Gold dot Dagor.
It is a great lens and hopefully you will find it for under 600 in great condition but probably not.
Dennis