When you look at the rodenstock information of the 135 rodagon you'll see that its listed for 4x5 and not for smaller formats. I remember finding some MTF curves for both lenses somewhere on the net and the differences between the two lenses were marginal IIRC. The advantage of making bigger prints with less column hight is a very big plus for the 135 mm for me. And in my personal experience it is an excelent performer.