My experience is that once printers get to more than five years old they are prone to get issues which are not economically repairable. I'm not sure what to do with my Epson 3800 which is four and a half years old and obviously out of extended warranty, but has been pretty lightly used. (It is incidentally my perfect printer and I would be happy to use for the next 5 years)
It hasn't had any problems yet but can i be confident it will chug on for another 5. If it develops a significant fault its probably going to be minumum £250 call out fee plus parts to fix. Would it be a better course of action to ebay it while still has some value and get 3880 for which prices are now softening, perhaps in anticipation of a new model. Although the fact that the 3880 has no direct competitors suggests that this isn't a big market so Epson may not feel need to replace.
I would add that some of the potential "improvements" people have suggested, such as the 900 series 12 inkset, would just make it bigger and no longer suit my requirements. therefore, i'm not really hanging out for a new improved model.
Also add I haven't got space or throughput that would justify 4900.