dunno about the poineer, but i had the cd4000 and i liked it. sounds good and there no complicated setting. im selling it, so if you decide to get the cd4000 send me a PM.
I've got an Eclipse 5435 that's an older version but just about the same as a CD4000. Its really good, but I'm going to be replacing it soon for a unit that will run an i-pod. Pioneer 5900 or 6900 is what I'm looking at so my vote is for the Pioneer.