Good that you have explained your context. It helps a lot with providing relevant insight. I have really only four suggestions to add here:
(1) The other Mark should explain the baseline of his comment more carefully in the context of the business you are doing. I would think it relevant to understand specifically what should be the expected fade-resistance of skin tones for prints on the papers you use under (a) dark storage in a closed album, and (b) framed on a mantle or shelf in the home exposed to daylight. If the number of such years is long enough for the life of the married and perhaps the half-life of their children, AND that is a benefit you wish to advertise to your clients (but perhaps not if they are fine printing and reprinting the master-file at Costco), perhaps there is not much of an issue here. But I don't know this answer.
(2) What did I mean by "baby-sitting"? OK, that was short-hand. I owned a 3800 (3880 is very similar) before I bought the 4900. I bought the 4900 because I wanted the latest technology and to return to roll-holding capability (I had a 4800 before the 3800, and a 4000 before that). The 3800 was the one printer of the lot I never even thought about. Turn it on and it worked. Nozzle clogs were rare, despite repeated, longish intervals of non-usage. When I received my 4900 I gave the 3800 to a friend for the cost of ink that remained in it. We got it all set-up in his house, it worked fine, and then he did NOTHING with it for over a year. Thereafter he told me he wants to get into actually using it. I was expecting real headaches. We fired it up, ran a nozzle check, and it was fine. We could start printing. With the 4900, my experience here in Toronto, sitting in a room well within Epson's atmospheric specifications, is that it can go a week without cleaning. Two weeks it will need one cleaning that uses little ink. More than two weeks it may need a couple of cleanings. Up to the end of last week it hadn't been used for five weeks and it needed two regular cleanings plus two power cleanings of the PK/LK channel pair in order to unblock the PK channel. But then it was fine. It has often been said that these are production machines designed to be in regular usage and that is true.
(3) It was possible to get excellent skin tones from a 4000, 4800, 3800, and now 4900. It all depends on the quality of the photograph itself, the paper you are using (GFS is great, but so are a number of others), the quality of your colour management set-up and your skill as a printer.
(4) Mark mentioned experience of ink dribbling with the 3880. I think this is worth further research to determine whether the problem is generic to the breed or was confined to small number of the total production to date. This is an enormously successful printer for Epson and I believe they sold a very large number of them, so the experience reports need to be read in context.