Actually, this is wrong.Metamerism is a totally different issue - and is not archival issue - but an ink / receiver (paper) compatibility problem. Metamerism can be eliminated - you just have to know what to do (use a good RIP and the correct ink/paper combination).
1. The rip has no effect on metamerism. The rip simply translate one language (tif, jpg, eps, etc.) into the printers page description language.
2. The couplers in the paper do effect the quality of the print, but will not remove metamerism. The couplers in the paper reduce dot gain, help to increase colour fastness and reduce drying time.
3. The pigments (the things that reflect the colour you see) used in the inks (especially blacks) that give the colours their resistance to fading have this 'special' reflective quality.