"....albeit at a lower cruising speed and altitude."
Not for nothing was it termed the 'Belslow'.
One of the most useless features of the ponderous old thing - the Machmeter.
Figures I have show an economic cruise speed of 315 mph at 24000 - that's 273KTAS which is around 190KIAS and M0.45..... With its 35.3 tonne max payload, the Belslow had a range of 1000 nm; with 10 tonnes, it had a range of 3600 nm - but wars would be over before it could lumber onto the scene.
Whereas the A400M will cruise at M0.72 and 31000 ft after a MTOW take-off - and carry 37 tonnes for 1800 nm or 10 tonnes for 4400 nm.
Which, as far as max payload is concerned, is 4% more, 80% further and 60% quicker........