What is the quality of refurbished all-in-one printers?

All of the factory refurb printers you see on the manufacturers sites will be from the past 2-3 years.

If you want to narrow down the date a little more, run the model number through a website such as http://www.cnet.com. They will most likely have a dated editors review of the product. That will narrow it down to within 6 mo of manufacture.