I'm not sure if the question relates to motion control of robots, human-robot collaboration safety or something else entirely.

If the question is about motion control of robots, our cycle time of 10-20 ms is probably too long as motion control usually requires < 1 ms.

If on the other hand the question is about human-robot collaboration safety, the product is likely unsuitable as this requires specially certified appliances.

If it's none of these two, it would be necessary to know more specifically what the setup is (fieldbus used, number of axes, etc) to come up with a realistic figure.

I work in the automotive sector. Not interested in human-robot collaboration at all, I was wondering whether this would be a suitable alternative to PLC control of spot welding and handling industrial robots. Even though the processing power of these things is likely to be better than that of a PLC, am I right in thinking that the overhead involved with running a proper (albeit fairly stripped down) OS would make it slower than a dedicated PLC? Obviously it has its place (and my curiosity is most definitely peaked) but controls hardware costs pale into insignificance compared to the capital costs of everything else in a car plant, so we'd need a pretty compelling case to switch.

This is definitely not the right place to use the RevPi System. It is designed to be a a PLC as well as an IPC or Gateway system. This mixture makes it unique compared to standard PLCs. But any system needing cycle times in the 1 ms range or below can't be controlled by a RevPi. But try and find any PLC which is able to speak nearly every known fieldbus or can easily be used as a gateway for IoT projects.