Spending one year on the 3.15% rate will cost you an extra €272000*(3.15-2.0)/100 = €3,128 in interest, approximately.
So there is no point in going for the 3.15% rate with €5k cashback when you can have the 2.0% rate with €2k cashback.
As many people here have told you before, stop focusing on the monthly repayment. The only thing that matters when it comes to savings is the amount of interest you pay.
If you try any strategy that involves not taking the lowest rate right now, you run the risk that that low rate will no longer be available when you go looking to switch to it in the future.