Cartridge Compliance Conversion

Rewires may somehow affect the effective mass of a tonearm, but what about the heavier counterweights? The original counterweight on the Rega RB300 is 95 grams and the Clearudio Turboweight for example is 135 grams... How does this affect the effective arm mass? Is it safe to divide 135 by 95 (equals 1.42) and multiply this with the original effective mass, i.e. 12 grams X 1.42 = 17 grams for the Rega? Or is it better to calculate the extra 40 grams as a percentage of the total mass of the arm?
Is there a proper definition of the term "arm effective mass" somewhere? I am quoting a frequently used definition:

Effective tonearm mass: The total mass of a tonearm's moving parts, and where along the tonearm that mass is distributed. Mass near the pivot point only slightly increases a tonearm's effective mass, but the same amount of mass near the tonearm's cartridge end greatly increases the effective mass.

If this is correct, shouldn't the counterweight added to the arm's mass since it is a moving part?
Regards,
Panayiotis

I am not sure this is the case. If we add a weight on top of a spring the resonance frequency of the system will change (decrease).
This is funny, I have posted the similar question before in a few forums but I never got a reply from someone who was sure of the answer!! I guess the question is really extreme.
BTW, last night I had a ZYX cartridge for test in my place. Its compliance is 15 and its weight including mounting gear is 6.2 grams. Befor that I had a Denon 301 with very similar compliance & weight, on the same TT. The Denon was making the woofers of my speakers flap quite a lot but the ZYX not at all.
I an not sure the published data for compliance can be trusted to the point that the calculations show us if a specific cartdridge would be a good matsh for an arm.
The final and only safe test is to get the distributor or someone else who owns it, to set it up on your arm and then review it, period. And I think that when we are speaking of cartridges with a price tag over say $600, it makes sense to expect the seller spend a couple of hours for you....