Micro Seiki MA-505 variants - any oracles around?

Wonderful stuff br3098, thank you so much for taking the time to write it all down!
I recently picked up an MA-505X, seemingly in mint condition (time will tell I guess) at a relatively reasonable price, but wasn't entirely sure exactly what I was buying due to the plethora of models in existence and an almost complete lack of dependable information.
I was under the impression that the 505X had silver wiring, but whether or no makes no particular difference.  I've never owned one but enjoy the sound of it a lot in a friend's system, so I decided it was time to check it out for myself.
Thank you once again, I'm most grateful.

Indeed, I'm sceptical too.  Fortunately I don't particularly care and in any case I'm unlikely to ever find out unless the arm turns out to be defective and needs to be disassembled.

Mine will by necessity be mounted on a Spacedeck, but presumably it will perform well there too.