I checked out the GRex - looks like a nice piece of work, but I would worry about it at this early stage of distribution. One thing is obvious - it is very powerful, and flexible, which is not always a good thing in a new product. There seems to be a lot of control logic and programming of the microprocessor. The block diagram looks quite complex to me. I know the gecko folks have loads of great experience in this area, but there are so many moving parts between the control software and the board, and then the board and the servo or stepper control, that I have my doubts that this is going to be a hassle free path. It's clearly the "bleeding edge." Still, it is an intrigueing piece of technology.