I have always thought the two would be very close in color and contrast characteristics. But here in the US, there is no present access to Maxima; so I am unable to test that for myself. The very slight differences being mentioned on this thread could easily be due to variables of emulsion aging prior to development, or inevitable slight variations in processing. Of course, Fujiflex is not a paper at all, but coated on polyester base, and that by itself creates a quit different look.
I'm a bit conflicted at the moment whether or not I want to do any color printing this year. Potentially debilitating tariffs are soon to set in, including for black and white paper; so I have to spend my darkroom budget wisely. Convenient RA4 kits are now back in stock, and I'd like to experiment with the new-style Super C product, which might be the same as Euro DPII. What still remains of my big 30 inch roll of Fujiflex
might or might not still be good.
Something which Flex, Maxima, and Super C N all officially have in common per spec sheet is higher resistance to pre-exposure yellowing than the cheaper papers like ordinary CA and Supreme. And since Super C "New" claims to have even better green and black repro than even its immediate predecessor, it should be substantially better than CA cut sheet products. But all of the cut sheet RA4 paper being marketed in the US is the same thin product line, despite at least 3 different private label renditions of it having turned up.
"N" (new style) Super C is relatively affordable, has a good thick base, and is readily available in the US in many rolls widths clear up to 60 inch. Its versatility might be one reason there is no push to bring Maxima into the country. Based on its specific predecessors, it should have very good display fade resistance, that is, if common sense is involved.
There are times the saturation and contrast of Fujiflex is simply over the top, especially for someone like me who often enlarges 8x10 Ektar originals. But oh, that wonderful 3D depth and incredible detail rendition when Flex is the ticket!