I'd like to learn more about your case, because several factors deserve further discovery in terms of product performance and service response that could be generally useful to the community.
Let's start with your print production. An average of 10 sq.ft. per month is too little usage for this printer unless you were very careful to make sure you used it at a fairly even pace of no more than three days or so apart from each printing session, assuming the printer is being used in a humidity range upward of 35%. Inadequate usage is generally understood by now to be a substantial cause of problems. But that's not the whole story, because usually one should be able to "nurse" the machine back to normal, suggesting other things could be happening at the same time.
One of the most important of these is the steps you took to clean the printer once you discovered clogs. What is the exact sequence of measures you used to try to unblock the printer? I ask because it is also known by now that some procedures can actually worsen the problem rather than resolve it, but the manual is not very good at delving into all of this.
I'd like to turn to the service issue. I don't know where you live, which Epson service center looks after you and who are the repair people you spoke with. But several pointers. I live in Canada, and we are covered ultimately by Epson America. A 4900 is a professional printer and based on our experience here, having bought one, you should be entitled to Epson Pro-Graphics support. I have been using Epson professional printers for the past 13 years and NEVER EVER has Epson America failed to respond to an email in a timely manner or to discuss issues with me over the phone. The service experience has been fine, and I have had substantial issues over the years. If you are not getting this kind of service from them, it would be good to understand why not. Technical advice and support have been available regardless of warranty status. Warranty status becomes important once repair or replacement comes into the picture.
Now, who are the repair people you dealt with, are they an Epson referred service provider, and what procedures and evidence did they adduce to conclude that your printhead is "bad". Sure it's bad if it's not printing certain channels, but what did they say about why it could not be brought back to normal? As you got the printer back with none of the colours printing, did you raise with them that the printer came back worse than how you sent it? What kind of packaging and transport was used in both directions? Was the printer properly prepared for transport following Epson's instructions both ways? If not, there may be more to discuss with the service providers. Sometimes these kind of companies need to be pressed very hard; don't fear doing so.
If the upshot really is that the printhead cannot clear with the usual methods discussed in the manual, if I were you, unless I had a lot time and money to waste, I would NOT try methods of restoring it that haven't been thoroughly validated and I would not buy a refurbished printer. You don't say what warranty conditions are offered on the refurb you are looking at, whether it qualifies for an extended warranty, and you have no way of knowing how good and thorough the refurb is. [I've had negative experience with three successive printers (all-in-one machines for office work) refurbished by Epson. I was under the last month of my warranty, so the problem got solved when they finally agreed to send me a new printer rather than yet another refurb. It works just fine and that ended the matter.]
If it comes to the point that you should buy another printer, think hard about whether you should stick with the X900 series or buy something such as a 3880 which is much less demanding in terms of usage and maintenance, yet makes gorgeous prints. True, there is no roll holder, but unless you produce a lot of panoramas you don't need it.
