Hi Paul
The Getrag gearbox used in the MINI One is the same as the gearbox used in the Cooper, so the revs will be the same.
I am not totally sure about where the revs are at 80 MPH but it's over 4000RPM. There is another thread about engine life and the high revving Cooper & One engine. If you want to read it you can find it here:
http://www.mini2.com/forum/general-discussion/97376-over-4000-rpms-my-cooper-highway-hours-every-day-ok-engine-life.html.
Hope this helps.
SuperCharged