While Flying Penguin is right, that VAS can be a problem under certain circumstances, I would also recommend to you going for FTX England. I have a similar system as you have, but to get an OOM, I have to use the PMDG 777, FTX England, Global & Vector as well as all Payware Airports in the London Area activated - and even then I might still get away lucky. With the Majestic Dash you should be well on the safe side, and with FTX England activated you don't need FTX Global or Vector in the covered region - it doesn't add more (in that area). Sure, there is a slight hit in fps but still perfectly flyable in the Q400.
Hope I could add to your decision. Happy flying!
Greetings,
Mario