Owned and sold both. I think that the Summicron shows more "Leica" charm...and the Elmarit holds the edge with size and critical/clinical sharpness. If you are a fan of Zeiss glass, you'll like the elmarit. If you like that rounded Leica look, you'll love the 'Cron. I think most Leica photogs would prefer the 'cron, unless size were of paramount importance.
If I had to have one back in my bag, it would be the 'cron...
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