i think my experience of flying only QF managed to gate check my overweight luggage. i've brought >10kg backpack on board but never had to gate weigh. Sometimes they check-in weigh my bags and i take them out and claim will pass them to relative/friend who took me to the airport - but always i'd put them back in out of their sightline.
another way to make it look like i'm bringing less is to put them in shopping bags...