The pressure sensor on the hottend is superior to any other method, because it has much better resolution (though maybe not better than the Beacon), and it can adjust to print conditions in real time, which no other start-of-print sensor can do.
EDIT: I'm not sure, this article says it can detect spaghetti just from the pressure difference, for example:
https://all3dp.com/1/nextruder-prusa-xl-deep-dive/
It also hints at detection of the height while printing.
They currently only use the load cells for bed leveling: https://www.youtube.com/watch?v=F7ETSVu04ao&t=940s
I could be wrong, but I would expect that the load cell readings would be far too noisy in order to determine the height of the nozzle while printing. Even if they were accurate, different materials would also behave differently due to different viscosities.