REALLY wanna jump into Sigma, but what about a decent RAW workflow?

Can't agree with that.

Would say that 8-bit TIFF is OK if the output file after processing is a webshot for posting, etc.

16-bit TIFF for considerable post-processing followed by a largish print.

For a late model Sigma not much choice other than SPP for conversion to either 8 or 16-bit TIFF and then off to your favorite Editor . . .

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Regards,
Ted http://tcktek.blogspot.com
SD10/70mm macro