There are circumstances when a changer is nice. If you're doing the dishes, cleaning, or doing something like that it's nice to be able to just load it up. Also nice for discs where you only want to hear a few songs each. The 5900 will make a magnificent CD player, but if your household is anything like mine, a changer will be necessary to insure domestic tranquility (ie my family insists on having one!).
I recently replaced my failing CD carousel with a DVD carousel, but I'm not wholly satisfied. It's a Philips, the one with upsampling for CD music. The problem is that it sounds radically different with the upsampling engaged, more so than you'd expect. It sounds pretty good w/upsampling, but not very good at all with it turned off. This shouldn't be. Also, it's very, very, very slow to recognize a disc, and the real kiss of death: it isn't very reliable with DVD-R/DVD+R. I burn a lot of DVD discs of various types, so this is a bummer.
BTW, I despise the magazine-style changers. I'd only have a carousel, but that's just me. YMMV.