fueldrinker (awesome nickname, by the way...
),
It is my understanding that the B777 uses a Smiths Ultrasound System. Apparently, neither the perfect solution, they need to fight with air bubbles, froth and sloshing. Maybe somebody else can comment...?
NutLoose,
MLIs and dripsticks are far less accurate, around 10% on the A330/A340 if I remember correctly. A FQIS in good shape brings that down to max. 1% at high quantities.
A380 will come without MLIs, which themselves can be cause for trouble.
Cheers,
J.V.