Unless there's no chance of getting the E175 certified, I'm surprised they're not trying to do so rather than operate a Q400. If you take LCY-EDI, do they really stand a chance against BA on one of their best performing routes?
Previous comments in the thread suggest there won't be any competition to DUB but I thought CityJet still flew that route & aren't planning to exit in which case can a Q400 really compete on a route which offers multiple jet operations?
INV & EXT seem strange route choices, whilst BHD sounds a very problematic route so there is a great deal of risk in the new LCY operation which presumably will seek to appeal to a very different market to their old LGW operation.
Time will tell if this is a good move or not.