A caution on the MS 505 arms for anyone considering one. I agree they can provide very good and convenient performance, but one thing to watch for.
When I got mine the stub beyond the pivot point where the counterweight mounts was not in the same plane as the arm tube itself. A search online was not helpful as some reported that was normal. Some online photos even showed the droop.
So I sent the arm to a trusted repair service (sadly no longer available) who confirmed it was not uncommon but not normal. They were able to repair it so the stub is now on the same plane as the arm tube.