Total €188,000 monthly €864.22 over 25 years
I don't understand, in all three types of loans it says fixed interest rate for 10 years. No one can say if you will still be paying €864.22 in the 11th year. The contracts may last that long, but the interest rates (as stated in the table) definitely do not.
At least 15, preferably 20 years fixed interest rate should be included.
It may be that in 10 years the interest rates will be as good as they are today, but if not, you suddenly have 3 out of 3 creditors on your back, all wanting X,xx% more interest. What then? Especially the KfW program 124 (if I interpret it correctly) is quite inflexible.
I also think it is risky to take so much money from Riester just because today the interest rates (compared to the other two loans) might be the cheapest. I would get more (the largest part) from the bank, secure a long fixed interest rate, and be willing to pay 0,x% more interest.
The question is, would a monthly burden of €1,000 already be possible today or is the nearly €900 already the entire monthly financing budget?