Colormunki, Printfab, RGB vrs CMYK

I have an Epson 3880.  After years of using Spyder but having to rely on uncontrolled commercial scanning...and getting inconsistent, frustrating results..I bought Colormunki and have profiled both the 3880 wth my RR paper and my old 3000 with it's own dye paper....with excllent results.  When I start CM and run the profiles I get RGB test prints to scan...as I expect.

BUT.....I aso have the (free) Beta (temporary) version of Printfab....with which I have succssfully printed a 5 foot pan, breaking the 38" 3880 barrier.  The Printfab driver associates itself with the 3880 as a separate 3880(Printfab) printer.

When I go to profile the Printfab-driver-3880 wth Colormunki....without any RGB/CMYK questioning...Colormunki prints out CMYK designated test patterns.  All of the profiles and switches I can find are set to RGB and Adobe. The result...printing in Adobe RGB...are psychedelic.

If I print setting the Printfab driver to CMYK(proof) I get ballpark but still off colors.  I have always printed RGB and have 0 exprience with CMYK.

I am asking Printfab how/why is CMYK automatically appearing in Colomunki...awaiting an answer.

In the interim:

1) Anyone using Printfab AND Colormunki and having this problem?

2) Is CMYK printing potentally equally viable for me as RGB (only) when I need to use Printfab to break the 3880 length barrier.  If I have no option should I pursue CMYK in this case?

Thanks for your thoughts.

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Peter Patricelli www.flyfishingfotography.com