Servo Motors - Mixing and Matching

To improve performance, we need to upgrade our multi-axis metal cutting machines to servo motors. But before we can even begin the selection process, we need to know if we should buy the controller, the amp and the servo motor from one supplier--or should we mix and match? We feel like the mix-and-match approach will result in the lowest upfront cost, but we're wary of integration issues. Do other OEMs have experiences they can share?