I don't know but all material I've managed to come across lists roller screws as having superior accuracy and repeatability to ball screws and due to the large number of contact points also exhibits better stiffness and load resistance.
But all this is way beside the point. What I wanted this thread to concentrate on is making a DIY version of it as ball screws are nigh on impossible to make at home and these suckers look a lot less complicated.
And here are some examples of what people have allready done, albeit much simpler and cruder versions of what the real deal looks like:
