Urm... I got around 50mpg (average was around 54 on my k6 Wee) when 2up and 60kg of gear holding steady @95mph on the motorway to Glasgow from Preston last year.
30mpg does seem a little low for a 650 doing a tonne.
Even the thirsty Varadero doesn't get into the low 30s unless I'm doing 70 in third.