You should add the AT33EV to your list.
The Denon 103 series is not a good match for the Rega or Technics arms at around 9 grams effective mass for the Rega and, well, much less for the Technics, however the Zu versions add enough mass to get you in the ball park.
The best match and sound, to my taste, would be the Dynavector 20XL. Second would be the Ortofon Rondo series, which were designed on the Rega arms, or even the Denon 301.
I never really understood compliance, high? low? effective mass? I have always put a cartridge on that seems to be well thought of and seen how it goes. So my understanding Virdian, is that you are saying the Denon 103 carts are physically too lite to sound good on the Technics and Rega arms? This is confusing since I have seen users liking the Denon on both the Technics and Rega Arm. Maybe adding a heavier headshell on the Technics makes a difference( LP gear, sumiko). If someone can explain this it would be great.
I am using Denon DL103 with Rega RB600 arm on Rega P25 with Graham Slee AMP3+SPU-1 phonostage with very very good results. Denon is my go-to artidge, you can find it for $150, so you have $350 already to invest to step-up like Bobs SUT and instantly enjoy superb combination for $500 mentioned.
It may seem that Denon does not go well with medium mass arms like Rega, but thats the fault of wrong look up to specified numbers (compliance, etc). Make a reaserch in forums and you find all that info. Actually it is compatible with medium mass arms. (But it supppose to work even better on heavier arms).
No, I am not saying that the Denon 103 series cartridges are too light to sound good in the Rega and Technics arms. "Good" is a subjective term, and many uses these cartridges with these arms and find the resulting sound "good". What I am saying is that the primary resonance is too high in these arms and bass response is not optimized, which is a bit more scientific than "good". If you listen to a 103 in an arm with under 10 grams effective mass, and one over 15 grams effective mass, you will hear for yourself the fully developed bass, free of the primary resonance in the later.