Darkmoebius,
In my system the Zu 103 just works a little better synergy wise. It's got a meatier, bolder sound that gives music a little more boogie factor--I'm using a table that is very laid back so its a welcome presentation.
With the 103D on my tonearm, there was a touch more detail and refinement but presentation was a little more relaxed. I think the 103D was probably a little better tonally too, though I haven't compared the two in so long. The 103D tracked just a touch better and quieter, but I ultimately felt the Zu was a better match to my system although the 103D is probably the better cartridge.
Ed,
I think I exchanged some messages with you previously on the 103D. I don't know the history of my cart I rolled the dice and bought it when it came up on audiogon with unknown hour but guaranteed to have some life.
The stylus looks great with minimal wear under magnification, but I don't know if it is the original or if its been re-tipped.