Fixed gantry designs are similar in most aspect and difference is depend on both what you need to do and how much you want to spend. But in this case I think it’s better to go with moving gantry (fixed bed) because cutting PCB do not need that much force and cutting depth is not that much and it mostly need to scratch PCB instead of cutting it. Steppers are good for such machine and will be enough.The machine will be fixed gantry.
It’s good to see some of other people designs and if you happy whit that then go and build. For PCB mill and drill most of machine can do it well (and off curse in this case accuracy is superior to power)