I can confirm the conditions of refurbs bought directly from Apple. At last count our family has seven refurb Macs including two MBPs, plus an iPad and two iPods.
"Lightly used" did not apply--each unit was spotless. All are still in service, including our frst refurb, a Beige G3 tower bought in 1999 and now used as a photo server.
I won't buy anything but a refurb if that option is available.
It's not as simple as that.
I've seen number of sources claiming that the components used in 2013 model are slightly different, presumably to resolve some of the issue 2012 model had.
Also, the 2013 are equipped with faster CPU by 0.1 Ghz.
Frankly, 2013-model will also have higher resale value than 2012 counterpart.
But again, yes, if the price difference is significant, I wouldn't hesitate with refurbs. Bought few of those and there was no way to tell that it's refurb.