I've been battling with a balance problem on my GS430SE for 6 months. Nearly sorted now (after over £2K spent on wheels, tyres, balancing, wheels (again), tyres (again), balancing, etc).
I am planning to take the car to ATS in Cannock for a final attempt, since they seem to be 'the good guys' (I had my MOT there recently and mentioned the owners club - they were really chuffed to hear that we rate them!)
By the way, is there anywhere on the website for us to post our recommendations - I think it would be a great way for us all to benefit, and might have helped me earlier in my struggle.