So if my math is correct it seems Easy Jet gets quite often load factors higher than (151/156)96,8% regularly to make the carrying those six additional pax along with the revenues generated by them in flight.
Regarding the second emergency exit ISTR from a conversation with an Airbus person in the 2002 Farnborough that the part of the fuselage containing the two pairs of the emergency exits was transferred from an A320 making it somewhat cheap (if there is such a notion in aviation). And just a thought regarding that deal, why Easy jet did not ask for exclusivity on the 4 emergency exits on the A319 (even maybe by paying a premium) obliging the other low cost to go to the larger and maybe more expensive to fill A320? Kindly take it easy with that answer since I only have a very very general idea of revenue but I think the smaller aircraft may protect the yield better (all things being equal less seats higher fare).
Thanks in advance