I used the version one version of the Leica Summilux 25mm f1.4 with a working aperture of f2.5. The shutter speed was 1/125th of a second and the ISO was set at 640. I think we were able to make it work.
In a moment of incoherence I sold my first 25mm Summilux to another photo blogger. When I got back into the system this past year it was one of the very first lenses I replaced. But this time I bought the second generation. Works better with DfD and it's better weather sealed. Optics are reported to be the same. Those standard angle of view lenses are crucial for every format. At least I think so...