I flew as SLF on both types and the 748 was much quieter, particularly in the cruise. Had a couple of rides on G-ARAY the second prototype during its time with Dan Air after it had not only been demonstrated around the world but had been leased to a long list of users. Sitting at the back of the cabin in a window seat and observing our progress at lowish level over the Brecon Beacons on a sunny day, we seemed to be crabbing all the time.
Speaking to the crew they said the aircraft was known to do this even in calm conditions. I thought they were just playing along with a passengers observation but for many years I have known someone who was involved with the 748 sales effort throughout its life and he had flown in G-ARAY hundreds of times. He told me this was a known behaviour after the aircraft returned from a lease in South America. The UK authorities were obviously OK with the situation as the aircraft continued in use for many years.