Summilux and Summicron lenses

Does anyone have the Summilux and Summicron versions of the same lens?

I have the Summicron 35 mm and 50mm and may be able to get the Summilux versions.

Am I crazy for thinking about this?

Is there that much difference in how the Summilux and summicrons render an image?

Any advice?

Regards

David