Patrick: Regarding comparisons between the 103R and the Zu 103 etc., this would be my educated guess on it. Just so you know where I am coming from, I own a 103R which is currently in an ebony wood body made by Uwe; my wood body is a first generation body-current wood bodies have been improved further and are available for $150.
I've never owned a plain 103; all the research I did before buying a 103R two years ago indicated the majority of users who had compared both stock cartridges felt the 103R to be superior. More refined, more detailed and more extension at both frequency extremes. That is not to say that the 103 is not generally very highly thought of and is definitely more of a bargain than the "R". I lived with the 103R stock for more than a year before slotting it into a wood body.
If you do the research at vinylasylum for views on either wood bodied 103/103R's or those that have been nuded and used only with a brass top plate, the concensus (and I would agree) is that either of those tweeks radically improves the performance of the 103/103R. It is such an extreme improvement that I have no doubt believing that the Zu 103 would clearly outperform the stock 103R. As well as putting the 103 into a much heavier and less resonant aluminum body (be careful-the Zu 103 weighs 14 grams on its own so you have to have the right arm/counterweight even to balance it out) they also "pot" the cartridge to further reduce resonance, which apparently improves the cartridge even further as reported by tweekers at VA who have done this (I have not done this with mine).
You've read the Dudley review so you know what he thought of it. Those that have wood bodied 103/103R's have replaced cartridges like Shelter 901, Koetsu Rosewood and Benz Ebony L, so that is the kind of company the wood bodied 103R and Zu can keep.
So you can do a Zu 103 at $399 or you can do a wood bodied 103R for about $270 plus $150 for the wood body. The advantage of the wood body is that it is re-usable if you want to scrap your 103/103R at the end of its lifespan and slot in another one, or you could go for something like a Soundsmith re-tip with a line contact stylus for $250 which is supposed to even further improve the cartridge.
The Zu, and I believe the potted 103/103R in a wood body if you do the potting cannot be retipped so that is a consideration. In effect, Zu is a complete throwaway after the 1000 hour stylus life, so that may be a consideration.
Also keep in mind that Clearaudio and "Magic Diamond" appear to be selling nothing more than modified 103's for $800 and $5,000 respectively, the Magic Diamond looking suspiciously like a Zu 103 to most who know the cartridge well. While Raul disparages the 103R halfway up the page, he can be seen gushing about the qualities of the Magic Diamond here in the archives; hence my problem with his opinion of the 103R as a crappy cartridge although, admittedly, it's performance is greatly enhanced by wooding or nuding it.
Hope that wasn't too long for you!