I just have to re iterate my experience with idas, i wouldnt recommend:
for me, they were even not that cheap.
im still using them (I cleaned them thoroughly with vinegar and a ultrasonic bath and changed the orings and then they work ok-ish), because I have to sell the thought of a spending spree on new clamps and arms to my wife :-)
i had a play with a friends nauticam arms and they are definitely in a different league then the idas ones. Very smooth movement. But they were quite new....