I've been avoiding Win 10 for everything, because pretty much no software I use has been updated to support it yet. I suspect drivers could be a similar issue, although that wouldn't matter on a brand new PC.
I tried out the tech preview, though, and it seemed more or less good. From the SCADA user's perspective, I don't think they would be interacting with the Windows OS much anyway.
I haven't heard any bad things about reliability of Win10, but I've heard a lot of complaints about the OS calling back to Microsoft with what you are doing. To be fair, they've apparently been doing it since Win 7, so avoiding the migration doesn't help you much.