Apart from an opinion,you cannot possibly compare arms like these in the home.
Under lab conditions with levels accurately conrolled and set it would still be difficult to say which was "better". You are not "listening " to an arm........but a system. One ingredient is always missing anyway......The Master Tape.
As for springs vibrating? If I set a spring in tension on any part of these arms with a clip attached.......do you honestly think your ears could pick it out?
My two arms at the moment are Rb300 and Michel Focus Unipivot. With the same cartridge and extensive listening as most of us are doing at home, there is no difference . Change the cartridge and bingo.....that is the transducer. Record decks themselves are the same IMO. My Ariston RD11 Belt drive is easily as good as my Lenco because you dont' hear them. It is the combination with the cartridge you hear or feedback , or lack of it.
RB 250 is a better arm? But take the counterweight off and it will be even better? People are making these things up. There is no basis for it except to speak with opinion or worse with authority or definitiveness.
There are many things at work in Hi Fi and lots of it is meaningless.
Ne'r mind It's a good job it aint important
No offence or criticism of anyone is meant here...........merely an alternative view. Nothing is Written In Stone
I think Roy Gandy must have a quiet chuckle at how serious this "armsound" all gets
TBH most of us that have had bundles of arms through the years are more stunned by the looks and engineering of them now.