Be careful what you wish for as the minute Easy Jet get on to the Manchester route its frequency will likely drop to two a day. The island needs frequent well timed routes you only have to look at Gatwick to see what happens!
Regarding London City the service since the introduction of the ATR has been poor although some of it is down to poor operations at LCY quite a few flights have been delayed out of there. I think Loganair are good operators but they do need to sort out the problems fast before people start to lose confidence. This is a vital route between the island and London and it would be a complete disaster if it were lost. The Embraer 170 would be great I don't understand why BA could not operate two rotations a day then reposition the plane to Belfast , Glasgow or Edinburgh to do a couple of rotations from those airports to LCY before returning to an evening rotation for the Isle of Man.