I can't speak to the RCA composite connector, as I never use that....
You CAN in-camera downconvert and get SD out of the S-Video port while simultaniously getting HD out of the HD-SDI and rear component ports... we do that all the time with our XLH1 feeding HD to a high-def LCD monitor (via component) and feeding SD to a standard-def Sony CRT (via S-Video) at the same time.
So... I would imagine that it is pumping SD out of the composite port as well. I'll check that to confirm when I get a chance.
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