The addition of ARB's and the amount that they will help drasticly depends on the choice of other suspension components. My first suspension kit on the ed30 was an Eibach coilover setup, they were far too soft and needed ARB's to lebel out the body roll, the Bilstein B12 kit that I replaced them with was 10x better and no need for ARB's. In fact it feels better than some mk5's I have driven that have every handling mod possible fitted and its still extremely comfy.
Suspension mods should be well thought out, not all components will work well together, its easy to ruin a cars handling by just bashing on every option available.
If I keep the car, I will be fitting a diff, continuing to fit good tyres and keep trying to work out a way to control the factory traction system manually via some sort of adjustable in-car module....... Still working on that one though!