I bought a factory sealed refurb from ebay that had a factory 90 day warranty. That was over 2 years ago, and I have never had a problem with it. I think that refurb units are inspected more closely than new units from the facotry floor... Just my two cents.
+1. I've had mine in for over a year and no problems. I manage a service department for an electronics/AV integrator and I'll tell you from experience that refurbs are just as good, if not better than A-Stock items.
Refurbs (B-Stock) are items that came back in on manufacturers warranty fixes and other types of cases as well. What the manufacturer does is fix the issue, fully test the unit as they would a new one and then box it back up for re-sale. Technically they cannot call it brand new and sell at full retail, hence the refurbished name and drastically lower price.
Refurbs are the way to go, but be sure that you are buying a refurb that was done by the original manufacturer, not some random electronics shop...
About the only thing I'll stay away from refurbs is/are flat screens, especially plasma's. Buy these new and definitely get an extended warranty 
There is a very reputable vendor on Ebay that sells Pioneer refurbs and that's who I'll continue to use. So far I've purchased 2 Avic's, an AVH-P4000, 3 GEX-P920's and a DEH-P4000...all of them work like they were brand new.