Hugo
You make some good points. I remember posting when go started promoting the routes, that it was difficult to understand their strategy. One thing that has become clear with the low cost carriers is generally they can create a market when they offer a new service. But to enter a market in direct competition with the oldest and wisest (?) low cost airline in Europe (ie GLA-DUB vs PIK-DUB) and start EDI-DUB, seemed optimistic to say the least. Once Ryanair announced that they were going to start operating why did go continue? In the press they started berating Ryanair and saying that they were offering consumer choice, fair enough, but don't do it at a loss - which is what go have admitted they were and are doing.
You mention forecasts, I would guess that in fact their traffic has been as good as they expected (anyone confirm?) but the yield will possibly have been below expectation - but again that's not surprising when you pitch yourself at the past masters.
I'm not condoning Ryanair's reaction to go's services, but I think it was naievity in the extreme of go to start operating into their backyard. They have been slow to pull out and even now are waiting another 3 months before withdrawing.
If BRS is working well for go, then EMA is likely to be a winner too. The question is how many more mini-low cost hubs can be created in the UK before the market is saturated. Or will any downsizing at BA/BD encourage the low cost carriers to start more services?