Rob,
I'm not quite sure, but perhaps they noticed differences in the past. As most know, I drop traceroute by default, simply because my router doesn't pass traffic until I've opened a port. So now I have udp/33434-335434 open, just for reject messages to bounce off my hosts.
I've observed improvements in round-trip-time, and mostly observed using the speedtest http://44.60.44.10/tools/mini/
This only changes the IPENCAP header (which is sometimes deprioritized thru networks I can observe), so tracing to my Public IP has no effect. This should only improve transport of the outer header to its destinations - thru Carrier links along the path that recognize the ToS bit field. The inner header should have its same priority.
- KB3VWG