I'm using two 3Nm motors to drive my X axis. 68V PSU.Steel gantry, with spindle, etc, probably weighs around 50kg. 2005 ballscrews, driven 1-1 through (from memory) 20T pulleys. Gives me about 5m/min rapids. That corresponds to about critical speed of ballscrews and corner speed of motors. 2010 might give me a bit more speed but probably at the cost of acceleration which is more useful if you are doing fiddly detail cutting.