Cosmo
You're quite right - I was trying to use a non pilot friendly analogy. Halfpint had dismissed the length of the runway as a possible factor and I wished to gently challenge that.
My line of thinking was that Air Force one might be operating at very light weights (this may also not be true) and that this might skew apparent correlation.
Having looked at the perf charts (thanks for the link, very interesting) I note that a 737 at 66.4 metric tons, SL, zero wind, f40, autospoilers and autbrake op would require about 1700m LDA.
The 747-400 chart shows that a 220 metric ton aircraft, SL, 0 wind, f30 etc would need about 1600m. (Knowing very little about 747s, I don't even know if 220t is a realistic arrival weight.)
Both are well with the 2195m available at Ciampino. I was surprised it is so long frankly, it certainly did not feel that long when I went there, but perhaps we made a downwind departure giving an illusion of a shorter runway, by the perception of less time from rotation to clearing the upwind threshold.