I've got a Leica IIIc and a Canon IVSB2. Both are really nice for street photography. I don't have a Summar but if the sample you're looking at is fairly clean there's no reason not to use it.
I recently acquired a post-war Contax IIIa with a Zeiss Sonnar 50/2.0 lens. The slow speeds on the camera are slow but the rest are OK. In use, I'm finding the Contax a little fussy compared to the IIIc, although that may simply be my lack of familiarity with the Contax. But what really blew me away was the Sonnar that came with the camera. What a beautiful lens!! I love the way it renders (I'm kind of a Sonnar fan anyway) and my sample is very clean. I like the lens so much I bought an Amedeo adapter so I can shoot it on my M mount cameras.
FS: Zeiss-ZM Planar 50 plus hood, Pentax MX, Voigtlander Ultron 40/2.0 SLII in Pentax K-mount, Takumar 100/2.8 and 35/3.5 lenses: See my ads in Classifieds
M3, M2, R2A, IIIc, IVSB2, & T, and assorted LTM & M lenses
Minolta XD11, Pentax ME Super, and assorted MD Rokkor and Takumar lenses, Rolleicord III, Rolleicord Vb, Rolleiflex Automat MX-EVS