Never forget that the A330/A340s are a couple of years younger than the "old lady" (and that the folks in SEA seem to be far more conservative than the chaps in TLS)...
An addition from my side (I am more familiar with the A340 than the 747s):
The A340 trim tank xfer is a brilliant thing in general - however, it also gives some headache as sometimes the automatic (!) fwd transfer won`t start automatically (!).
Yes, it`s for drag reduction (reduces required downforce of the THS); the MEL says you have to consider 1.5% more fuel burn when the TT is inop (for whatever reason). Some guys were looking into flight planning data and came up with a worst case scenario of about 0.8% percent if I remember correctly.
Apart from the CG control, there are tons of differences as already indicated by QAVION - some of them:
No "real" tank-to-engine-feed during normal operations on A340s ever. Only when you shut the emergency-isolation- or split-valves (fuel leak suspected!), you seperate the two feeding inner tanks into a fwd and an aft section each to feed their respective engine (fwd tank feeds inner engine). This has been a playing ground for a number of FCOM revisions lately...
Only one fuel line between wing area and APU/TT on the `buses - one of the big trouble makers on the classic A340s (-500s/-600s will get two lines to feed the APU and operate the TT seperately).
All "main" (wing and the two center tank) pumps are of the same type - there is nothing like main boost pumps and override/jettison pumps as on B747s and B777s.
BTW:
A330s are fitted with the same FCMCs (Fuel control and monitoring computers) and have the same CG control systerm.
Cheers,
Jettison valve