Although purely subjective opinion I tried the Summilux you mention, didn't like it so much and actually kept my DR instead, felt the DR had much more of the signature and personality I strive for, especially for black-and-white work, that I happened to prefer. The Summilux was a great lens don't get me wrong however for the cost I just didn't want to keep it because I was very very happy with my DR. The great thing is you can try the Summilux and easily sell it for what you paid for it so if you want to give it a try I would recommend you do.