Setting a ToS value for control traffic does not effect the BD process between WXC devices. You are just setting a ToS on the 'internal operational' traffic we use between devices to peform healtch check/tunnesl status/etc. This command tags the port 3577/3578 traffic.
The WAN perf probes run outside of the tunnel, so they are not done per traffic class as you wish for - sorry.
Danny Jump Technical Marketing Manager - Access and Acceleration Business Unit