G'day Andy.
Sorry but I guess it depends how you read what I wrote. My fault - goes to show how hard it is to imply subtle nuance on the web. I'm talking about cruise flow flow rate at high altitude as compared with holding fuel flow rate at 1500'. Most jet aircraft (well, mine doesn't so I'm assuming the rest are the same) don't have cruise data for 1500' but comparing cruise data at max endurance cruise ie. holding fuel flows at say FL300+ as compared with holding fuel flows at 1500', the lower fuel flow will be achieved at the higher altitude.
Can't remember the aerodynamics and BGT to explain it but primarily jet engines are more efficient the higher you go.
Hope this helps clarify things.
Cheers.