This site is a great resource for advice on CODEC performance.
http://codecs.onerivermedia.com/
Part of the decision of what codec to sue will be based on workflow. For example most people would recommend using the Huffyuv codec -
http://en.wikipedia.org/wiki/Huffyuv but this would not fall easily into your workflow as ideally you want to capture to the same codec as you'll be archiving with.
If I were you I'd continue using the Blackmagic 8bit uncompressed codec; storage is cheap, especially offline storage.
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