My collapsible Summicron (1044xxx) arrived with so many front element cleaning marks I considered sending it back. Quick check on the R-D1 convinced me to keep it. It is the sharpest of my older LTM lenses (Summarit, Summar, Nikkor SC and Zeiss Sonnar - admittedly none perfect).
The only knock on this lens - and I have heard this from other owners - is that the aperture ring is ridiculously tight. Though not so much that I feel the need to send it to DAG for this one annoyance.
- John