From a purely financial point of view, it is a poor deal. If considering this, it would be purely from a personal circumstances perspective - how is your income going to change over the next 5 years, how is your health, do you have any dependents to whom you'd like to leave an inheritance, etc.
Based on the finance alone, your mortgage repayments are €90,000 for the remaining term of the mortgage, after which, you are left with an asset worth €165,000 and can live rent free for both lives anyway. The property will obviously change in value along with the rest of the market - probably up but, possibly, down.
Then, if you choose to take the offer, there's the added complication of the detail of the contract. What happens if you want to move home? What happens if one of you needs to go into a retirement home?
Personally, I'd continue paying down your mortgage and keep the house. The flexibility in owning the house outright as opposed to the mere right to live in it rent free is worth the sacrifice involved in making the monthly repayments over the next five years.