Going to be fitting my new weitec coilovers after Christmas, but as title suggest is it worth changing ball joints at same time? I remember when fitting my springs and shocks on my mini that I actually broke the boot on the ball joints and had to replace them a few weeks later.

I would as the car is apart anyway only takes seconds.

if they need replacing (or will do soon) then it makes sense as above whilst you've got the car in bits - only have to do the geo once then..

.. and if you're going to really get the car handling nice go for the superpro adjustable ones so you can dial in some neg camber on the front.

and get some S3 console bushes.