Mike..
I agree with both you and Art. As we know the desktop PC as we know it will possibly soon be extinct. With that said, there still will be a need for professional workstation PC's. Especially the versions that will support massive GPU video cards for the medical industry. They will not be the smallest or the cheapest computers in the marketplace, nor should they be. I do feel that market will leave some options for PC based small CNC control.
I am not sure I would be comfortable betting my livelihood on the limitations of a USB data transmission stream, or my checkbook on the proprietary controller. But, if those were the only two choices, I will take the stable one.... proprietary. This is due to the decline in recent years of PC's to transmit CNC data over USB while at the same time PC hardware providers have been telling us the data rate is going up. It may be, just not for the type of data we need and the speed we need it at. Couple that with the fact that the Windows OS control priority of the USB buss as it sees fit and its a wonder that any code gets cut. To me that is the advantage of WinCNC's controller, it doesn't require or use up much processor time other than to pass thru our favorite text files. Its a good fit for those that want more than the cheapest thing out there and might not be able to justify a 5 figure proprietary controller.
Gary Campbell
CNC Replacement & Upgrade Controllers
Custom 9012 Centroid ATC