Your investment mortgage is keenly priced, ultimately you will have to address the capital repayments, will the tenant pay most of the mortgage on a capital and interest based mortgage over say 15 to 20 years..., what effect does paying off the mortgage have as it would relate to taxation...as against now..
I would not pay down this mortgage, you are under no pressure, you have funds spread across other State guarantees rather than any reliance on our Irish state guarantee, personally I considered a transfer of funds out of Ireland but I didn't follow through, I have diversified the deposits very similarily to yourself, I don't really see that as hoping for the best but who knows...,
It is comforting to have that cash, hold onto it.