Hello Raul,
Sorry to say this, but unless you give me the serial# I won't be able to tell you the eff. mass of that particular arm. Since this arm was likely sold through an importer/dealer I wouldn't know who the customer is(nor do I care). I assure you that, even if I knew, I would not disclose the identity(and why should I?).
As for the eff. mass of my arms: The Reference can be ordered with armwands ranging from 5 - 50(!)gr. eff. mass. So there are many different ones around that certainly won't suit just any cart you care to mount.
And who is "we", as in "we do these tests without influence"?
Make shure that gentleman sends the instructions along, too...
Cartridge recommendations simply refer to proper matching of the physical parameters, not the sonic properties.
Waiting for your reply,
best regards,
Frank