OK, your LTV is 65%(100/155)
The best deal is AIB 3.3%
That would save you 0.4% a year or €400.
But AIB will pay €2,000 towards your costs, so yes, it's worth it as you start saving immediately.
But...
Does AIB accept switches from EBS? I don't know the answer to that.
EBS will announce some repricing of mortgages shortly. My gut feeling is that it will not benefit existing customers, though.
What about Frank
If Frank starts lending at 2.8%, then you will save €900 a year.
I gather that they will not contribute to your legal costs which should be around €1,500.
So for an investment of €1,500, you will get a return of €900 which will take you just short of two years to recover.