The open comb in the Mühle OC is the same as used in the Merkur 15/25C-42N; it is made by Merkur but way better finished on the Mühle.
The safety bar head on the Mühle (& EJ) is a different design; there is a difference in the curving/ angle as well as in blade gap. Most important; shave is different. Not by much but not hard to notice.
Frankly I do not get it that you can't see/feel the difference between those when you have them all at your disposal.....
I must to the barber's, monsieur, for methinks I am marvellous hairy about the face