Wayne, Thank you for this description, so well measured and reported, and for your posting of your Scripps Pier landscape example. One might have expected a "grayer image" based upon your ink ratios. The ink use ratios you list, while I'd not quantified them as you did, seem to mesh with my own portraiture printing on the 4900. I'll consider the 700cc inks on a per-color basis, if I do buy the 9900.
Mike, I am with Ken on the 4900's paper cassette being the one and only thing that you'd miss if you own only the 9900. I've printed enough single sheets on a colleague's 9900 to say that the 9900 is no worse than the 4900 in handling single cut sheets. In this instance I am comparing the rear manual feed path of the 4900, with the one and only sheet path of the 9900. 9900 owners will need to elaborate, but I'll testify that the 4900's rear path is inconvenient for me. The rear path is needed for heavy media, as heavy media won't feed from the cassette. In loading thick media, the transport often fails to grab the paper, and some downward force during the entrainment assists in the "grab", often at the cost of introducing skew. Epson tech support has acknowledged the rear path problem in my calls to Epson, as I was able to report that even Epson-branded stock like Ex Fiber, Cold Press, and such, all exhibit the problem. There is a workaround that, in my opinion, is very time consuming and *not worth it*. Right now I am, for example, I'm printing greeting cards on Epson Cold Press Natural 17x22 sheets from the rear path, and I need to personally nurture each sheet load pretty intently, and re-attempt 50% of the time. I've experienced no such loading problem on the 9900 when presenting sheet-cut papers like Cold Press or Ex Fiber. BUT, the cassette path is a massive time saver when the media is appropriate. Recently I completed 200 prints on Canson Baryta Photographique 13x19 media in a weekend, using the cassette of course! Try that on a single sheet at a time basis.
Again, as Ken says, the 3880 might be a better purchase than the 4900 would be for someone not benefitting from the cassette, or someone pressed for space. I've identified my ignorance that profiles can't be shared between 4900 and 9900, but I think I might better understand relationship between 9900/4900 than I would between 9900/3880 based upon common ink sets.
Again, thanks to all.