Must admit it always strikes me (and I can understand that it doesn't fit with their fast turn-around business models) that the lo-co's seem to usually fly with half-empty (or less) holds.
Flying with both RYR and EZY, I've rarely seen the rear holds being used, even when the pax load is high.
Isn't there a revenue opportunity they are missing out on by not carrying at least some freight/mail etc? (eg, small express parcels that could be loaded quickly by hand)