Don't know much about these things but I agree about the ballscrews, I think it's guaranteed to give a better result than not having them.  Everything is effectively geared for finer movement and I suppose with it being on a thread, the chances of overshoot are just about non-existant.

Good luck with the rebuild.  I keep eyeballing mine ever since this thread, I should be able to get the ballscrew out without touching anything else.  If I can find a local engineers that can examine the ballscrew, I'll remove it.