2BE or not 2BE
Regarding your argument about turboprops and jets I'm not sure how valid it is. I believe that the q400 sector times from BHX to EDI ( for example ) are only about 5 minutes less than the 146, so given 8 sectors a day that only leaves you with an extra 40 minutes airborne time to earn more money - perhaps a BHX-MAN route might just be fitted in. Admittedly an Airbus or Boeing might gain more time but would require a huge investment in marketing to fill it, and marketing seems to have died down after the flurry in the summer.
If you want to get more sectors in on a network such as Flybe has the only way is to have a longer flying day - most flybe aircraft are back on the ground by 2100hrs. But to do that you need to attract passengers to fill them.
Don't get me wrong - I'd rather fly a jet and the way things are it looks like I might end up flying a Q400 instead but the problems are not just about aircraft types - management and marketing are the two words which spring to mind.