gate 22, I agree that flybe suit BHD more than Ryanair but unfortuneately the airport doesn't care about who's best suited for their operations in terms of aircraft size, the only thing they care about is incresed passenger numbers and more businness from other airlines (which if my calculations serve me correct it equals more money for the airport).
I do think they'll compete well, but I'd say Aer Lingus will have to work on it for a couple of years before they could have bmi give up even one flight to Heathrow. bmi have just bought BMED and this will mean the BHD-LHR flights will be feeders for the new routes, and if they start longhaul flights from Heathrow as well then the route is in more demand.
ps. is it flybe who have been told to give up their businness lounge or another airline, to accomodate Ryanair?