I run a couple of Sony CD-XP 450 mega changers through the optical inputs of my 861. The only drawback to using the optical connections (there are no coax outputs, though convertors are relatively cheap) is that the two changers can't control each other (that requires an analog pass through from one to the other, which sucks (not that I've even bothered trying Sony's DACs)).
As for my experiences with them, the fact that I own two is due to the fact that I bought one, loved it so much, I bought another (as I suddenly started buying CDs again and filled the first one up). You won't look back from having all your music ready to go.
Typing all the CD title and artist names in is quite a pain (even with a keyboard). However for the terminally lazy a company called Nirvis (
www.nirvis.com) make a nice controller for all Sony S-Link equipment. This can enter the names in from CDDB amongst a wealth of other features.
TomO