It's a slightly strange route for Manx2, given that they're not known in either market. But considering their collection of Lets and Dorniers, it might work. Any time I used the route when Aer Arann were flying it, there was around 35-40 on board. With their aircraft having considerably fewer seats than that, it should be possible to decently manage the yield.
Given that the aircraft has to get to either Cork or Galway, is there any word of them opening up routes to the Isle of Man or Gloucester from either airport?
I wonder could a 19 seat plane work to any other Irish airport other than Galway. Sligo perhaps?