I don't doubt for a minute that adequate research into Southend's catchment area hasn't taken place.
Flybe has the advantage over the likes of EZY and Ryanair in that the Q400 can operate quite happily in and out of there, whereas a fully loaded 737...... forget it!
Best of luck to Southend. I hope they succeed.
Foxy
PS what are the chances of them getting their CTZ back???