Image quality of N-color water based ink inkjet printers is still at the top compared to (Eco)solvent, Latex, UV curing, ink printers. Partly because the last do not have an ink set beyond CcMmYK or CMYKRB or one of those and an extra white ink. The other factor is that some binders are not that transparent. The optional white ink is not increasing the gamut other than laying a white fond when no white medium is present. If there is competition it is from (Eco)solvent models as their gamut comes closer and third party inks set the low ink price level in that category. With more Latex printer models becoming available (HP, Mimaki, Ricoh and more) that may change in time. While more Eco due to less (aggressive) solvent used the energy use of Latex printers has been considered high. My 5 cents.
Met vriendelijke groet, Ernst
360+ paper white spectral plots:http://www.pigment-print.com/spectralplots/spectrumviz_1.htm
september 2012: Photokina updates going on for at least a month