Munt,
Mate I think you misread me; I was talking about taking on 772ERs to do current 744 runs. I would agree that non-ER 772s wouldn't have the range to take on long 744 runs.
Hence BA are running 772ERs to Sydney.
I'm not sure the 333 has the legs of a 772ER, does it? I agree it's a fine aircraft for - let's call them 'long mid-range' - runs.
I'm thinking of something you could put on (say) Brissy-LAX and fill running 2 donks, rather than something running 75-80% with 4 donks; I agree that it is pretty well sized for runs out of middle-sized markets (eg. Perth, Brisbane, Adelaide) - that point-to-point stuff is what it was made for, after all. The 772ER-as-744-killer comes into its own where you do not need 380-400 seats on a long run but could reliably fill 300-350.