Buster,
240,000 lb is about 109,000kg - so not much difference.
In this case, I'm more referring to shifting and transferring fuel, but having the ability to shift military cargoes of other types.
If the A330 tanker could do all the C-17 can do, off the same sort of strips, then that'd be just as good. I'm yet to see an A330 back itself off a stand.
I agree there is a need for a number of airliner-type airframes to rapidly move personnel and their immediate needs; however there are loads of airliners around which can be chartered at short notice for this purpose. The same can't be said for long-range transport direct into theatre, or in-flight refuelling capability.
What I have trouble understanding is the cost thing: the RAAF, f'rinstance, is spending a bucketload on each of a small number of C17s and A330 MRTTs. I would've thought it more effective to get a bigger number of multi-role C17s (if such were available) - thus giving you up to, say, double (if the total order was 8 frames) the brute airlift capacity plus the IFR capability, plus a small number of straight-off-the-civil-line (so cheaper) A330s (with fully contracted civil maint) for troop movement, etc.
Whilst QF or whoever will be able to handle deep maint for the MRTTs, how will they get on with gizmos like the boom? Meanwhile, you'll have a small number of dedicated RAAF engos doing C17 stuff and then probably sitting on their backsides in between U/Ss.
And the same can be said for the RAF and USAF (tho' clearly the latter there is a very big C17 operator so doesn't have the worry about a small, dedicated C17 maint group).