Galway is now quite the hotspot of development, so don’t rule it out, plus it’s a great city to go out in!
Regarding organising it, I belive that some of the Galway companies previously organised a smaller game dev event, so they already know the ropes regarding organising a larger one.
The only problem is that Galway is the official ‘Middle of Nowhere’. Getting there from the international airports would be very difficult for speakers. Belfast takes seven hours on the bus and it’s almost four hours from Dublin.