I shot 1/2 dozen rolls with the 21f1.4 - R4M combination. It work quite well, but yes, the hood intrudes quite a bit in the lower right hand quadrant. You quickly learn how to "sweep" the camera a bit to check what's hiding behind the hood though. With the M2 I used the top-mount finder - obviously not the same blockage, though the lens is clearly visible in the lower edge of the finder. I did prefer it with the R4M - in spite of the blockage.