Financing offer special annual repayment possible

Hello,

so we have decided to buy our dream house from the developer.
Total house costs ready to move in 770,000 euros, additional purchase costs come on top as well as garden (without terrace, which is already included) and kitchen. Equity 180,000 euros, net income between 7,500 and 9,000 euros per month. 40,000 euros still available as reserve.
So we need a loan amount of 650,000 euros.
We initially plan a monthly rate of 2,800 euros, so there is still some room for special repayments or saving for the children's education, car, etc.

Offer from the bank:
15 years 1.66% or
10 years 1.24%

Now the question for us is whether we should take the 15 years (which we currently tend to) or split it, e.g. 60% of the amount for 15 years and 40% for 10 years. This was recommended by the bank advisor.
How did you do it? Is the bank's offer okay? 5% special repayment annually possible, 12 months no commitment interest, free repayment change up and down 3 times during the term possible.

The interest rate is acceptable for the loan amount. Why do you want to split? Kfw? Repayment? Term? Do you want collateral?

I don't understand the split either, why such pressure to repay within 10 years when it can also be done this way. What is realistic for special repayments in your case? How about the kids and the changed income?

Actually, we want security. Kfw is out of the question, it is only a Kfw 70 house. The bank advisor said that with the splitting we reduce the risk if the interest rate goes down, if I understood correctly. The children are 7 and 9 years old, there will not be any more. We probably will not make much extra repayments per year, maybe 2000-5000 euros. Income is fixed at 7500 euros, on average we come to more since my husband also receives special payments that always vary a bit.

KfW is out of the question, it's just a KFW 70 house

And yet there is the home ownership program, which has nothing to do with saving energy.

we reduce the risk if the interest rate falls

You have a special right of termination after 10 years with the 15-year loan. If there is really a better interest rate after 10 years, that is still possible. I would rather go for the security of not having to look for follow-up financing after 10 years and then again 5 years later.

If you want security, then buy a 20/25 year fixed interest rate.

Risk of falling interest rates - funny argument! - when you can get out free of charge after 10.5 years anyway. How much lower do you think interest rates will go? What if after 10 years the interest rates are back at 8%? Will the advisor then pay you compensation?