Color rendition with the Foveon true-color sensor in the Sigma DP* cameras has always been a bit of a voodoo affair, to me at least.
To my review of the Sigma DP1 Merrill in Guide to Mirrorless (ALLVIEW) I’ve added a side-by-side scene in which I get reasonably close in matching the Sigma DP1 Merrill color to the Nikon D600. Details on the adjustments are documented.
As for resolving power, that has not occurred to me yet. :;