The osmosis on humidity conditions might have come from my L-L article on Epson 4000 Printing Costs, where I discuss this. It was based on advice from Epson America. I have now up-graded to a 4800 and I am watching the cleaning and printing ink usage factors carefully - same methodology I used in the past on the 4000, as explained in that article. I have only had the 4800 for about a month so it is premature to report any conclusions about comparative performance regarding costs and clogs; let me just say that so far so good. I work only with matte papers so the ink change business is a non-issue for my workflow. Note, however, that anyone changing media about 14 times in a year would pay for ImagePrint within that time period, without investing in the cost and space of a second printer for that purpose alone. If I needed to make frequent paper switches and/or needed the other workflow advantages, I think ImagePrint 6.1 would be a convenient and economic investment.
As for comparative print quality in colour on matte media, both the 4000 and the 4800 produce excellent results using the Epson printer profile and a properly profiled and calibrated monitor. Based on test prints I have made with both printers using the same Gretag-Macbeth printer test page, the 4800 provides a slight but obvious improvement in colour gamut and grey neutrality.