What is the appeal of the Denon 103 cartridges?

By audition, the Hana EL (at about the same price level) is better. You may wish to learn more about this amazing cartridge. 

Don’t under-estimate a Grado Black or Green either.

Comparing cheap Grado Black (or Green) to expensive Grado Signature XTZ anyone can understand why the cantilever and stylus profile make so much difference in sound. The difference between lower and upper range of Grado cartridges is huge. When a cartridge designer is making his top model it must be (and it really is) superior to the entry level models. But those models looks almost identical and even styli are interchangeable.

For the same reason anyone who paid a lot for an expensive cantilever (to replace Denon stock DL-103 cantilever and stylus tip) are all claimed the upgrade in sound quality is obvious.

Don’t forget that Joseph Grado invented first Stereo MC cartridge and patented it. But he’s making an MI cartridges simply because they are better almost in every aspect. His top Signature XTZ was $750 in the 80's. 

I had a Hana EL. Nice sound though far less dynamic than a modded 103. My favorite 103 recieved a new JVC aluminum cantilever with nude shibata and Stanley Engineering closed Cocobolo body. Just lovely sound. 

My all time favorite carts however are as follows 

1. Audio Technica ART9
2. Klipsch MCZ-7 (retipped with ruby cantilever + micro scanner II tip)
3. Phillips GP922 (FGS special retip
4. Supex SD900 Super (shibata retip)
5. Grace F9 (boron cantilever,  micro ridge tip)
6. Fidelity Research FR-7
7. Fidelity Research FR-1 Mk3F

Thanks. Currently I'm enjoying my AT VM540ML. Tracks nice and a good general "all arounder". I play everything from 40's 50's Jazz-Big Band, Classical and 50's-90's classic rock. Vintage records that are not in perfect shape play great. 

I have been thinking for a while to upgrade to the ART 9 and keep the 540 for less than stellar recordings. I have a Technics 1200GR so switching headshells and adjusting tonearm would be a breeze. 

I think each cartridge must be good or bad in its original form, each time someone changing a cantilever from one to another the result is a different cartridge and the sound is not as expected by the designer of the original cartridge. Some people think they are always smarter than cartridge designers or they think their re-tippers are smarter than people who actually design cartridges. The problem is that a cartridge is not good enough, simply not the best model or does not sound as expected. 

Many cartridge designers explained why it can be a disaster, refirbishing is very bad idea for almost any high class cartridge. For a low class cartridge it can work, but If a cartridge is not good then it can be replaced by a much better cartridge, no need for frankenstein that retippers are offering. 

Stick to the original cartridge and if you don't like it buy another original cartridge. This process can take entire life, because hundreds of great cartridges are on the market (lomc, mm, mi, moving flux, strain gauge etc) and you never know what you like until you will buy it! Some carts like IKEDA or Decca does not have a cantilever at all.