We needed accuracy, something the normal rack&pinion style doesn't provide, hence us going with ballscrews on all axis. Only problem with going ballscrews is that it's limited in length as you can imagine, the longer you go the more your rapid speeds decrease. We ended up with 1m x 1m in travel, allowing us maximum rapids of 30m/min with maximum feed 20 m/min
Machine accuracy with this particular setup is between 5 - 10 micron

Only thing holding us back at the moment is our servo motors which only has 750w , not nearly enough to handle fast accurate feeds, but we'll upgrade those once funds are available.