1st option: 4 color (C M Y K) x 2
Why x2? You can have two sets of cmyk because there are 8 ink cartridge slots on that printer and this way you get faster printing.
2nd option: 6 color C M Y K Lc Lm
For richer, fuller colors? Yes. Yes, but mainly you get much better blending or gradients and much richer skin tones. Do customers see it ?? Sometimes yes, sometimes no. Much depends on your files. We've had and have 4 color and 6 color and most of the time, we can see a big difference in certain areas.
3rd option: 8 color C M Y K Lc Lm Mt(Metallic) and W(White)
Does the Mt and W require the Lc and Lm, or could you do CMYK + W, or CMYK + Mt?
Yes they do require the Lc and Lm, that way you can use all the metallic collors form the roland metallic color pallete.