I would agree with the dog and pick up truck statement. Unfortunately, the JMW arm is not in the high-mass category. Oh, it might be high-mass compared to a Black Widow tonearm, but not in the broader sense. An arm(JMW) that is around 11 grams effective mass, is a medium mass arm. Heavy arms start around 12 grams effective mass, and higher, and the higher ones are more suitable for a very very low compliance cartridge like the DL103. I did some checking on the ideal combined mass of a DL103 and tonearm, and it comes to about 21.5 grams. Since the cartridge itself is about 8.5 grams, that would make a tonearm of about 13 grams optimal for this cartridge.
Now I don't say that a lighter arm couldn't handle it, but it would lose some of the dynamics and bass and detail in the process, from being overdriven by the cartridge.
Also, I would venture to say that since the JMW is a unipivot, it will have azimuth changes during play with this cartridge. It is unavoidable with this combination of ultra-low compliance and unipivot design. It's going to rock and roll.
I have owned and used a number of these Denon cartridges, including the DL103 and DL103R, and am very familiar with their needs, and my viewpoint is not strictly theoretical. I used them on arms that were 11 grams, and ones that were almost 12 grams, and the cartridge was clearly overdriving both of those arms. And they were gimbal-bearing type arms, which give far better stablity, and at least don't change azimuth during play. This led to my development of a tonearm mod, that was required in order to get the proper result from my use of this cartridge, with my available tonearms.
Suffice it to say that I am in disagreement with Art Dudley and his findings.
In the end, if you like what you are using, that is all that matters. I have had this discussion with many JMW owners over the past 2 years. This subject always comes up. It is very difficult for me to be as diplomatic as I'd like, and still tell the truth. I try to help, but people don't want to hear what I have to say.