I get the same noise you describe with mine (same car as yours BTW). Also had ARB Bs replaced. I still suspect it's an ARB issue - some wear somewhere (!). Just can't think what else it can be, corrosion on the ARB, slightly bent ARB? I'm tempted to replace it and see if that fixes it. A colleague's Seat had a similar issue, fixed by a new ARB and you could see slight corrosion that allowed some small movement (on that car the bushes fit into a sort of flange and it had worn off allowing the ARB to move a little).