My machine has a welded steel gantry that weighs, at a guess, somewhere around 60-70kg all-up. I drive that with 2 Nema 23 3Nm steppers, driving through 1-1 belt to 2005 ballscrews. I am currently running at 5000mm/min rapids. Haven't yet tried faster but that was the design target anyway - approaching critical speed for that length ballscrew and also corner speed for steppers. I could probably go faster with 2010 but at the time I starting collecting the hardware these weren't so easily available. Machine is still very new so haven't explored cutting capacities yet. To be honest, at the moment that seems fast enough for rapids on my size machine (cutting area 1500x750) but I get the impression that faster could be useful for cutting wood. Given that my old router could only manage 900mm/min, 5000 seems like lightning! Can't remember what acceleration is set to.