^ Some of those privacy concerns can apply to Win7/Win8.1 now, as there's been some recent updates that include more telemetry.
Though I have yet to find an actual article done by a trusted resource using WireShark that shows exactly what data is being transmitted and such. The only thing I'd be concerned about is the unique machine ID being sent even when a lot of the telemetry stuff is disabled...but there's been a lot of little utilities to try and remedy that - whether they're actually successful in blocking that without the end user blocking it at the firewall/router level is another question.
Though I have yet to find an actual article done by a trusted resource using WireShark that shows exactly what data is being transmitted and such. The only thing I'd be concerned about is the unique machine ID being sent even when a lot of the telemetry stuff is disabled...but there's been a lot of little utilities to try and remedy that - whether they're actually successful in blocking that without the end user blocking it at the firewall/router level is another question.