Refinance KFW loan (153) with an annuity loan?

Has anyone of you ever done this?
With some KFW loans, special repayments up to 100% can be made (except for the home ownership programs 124). If you have a "bad" Kfw interest rate, meaning you took out the loan 3 or more years ago, you could repay the KFW loan with a normal annuity loan through a special repayment. This way, you could save a few euros?
Does anyone have experience? What needs to be considered? Are there problems because of the mortgage registration?

Problems only arise with the interest, since this usually concerns subordinated loans from a bank (typically your main financing bank). The land charge is already registered in favor of the financing bank. You will probably not find a third bank that only finances subordinately.

Has anyone of you ever done this? For some KFW loans, special repayments of up to 100% can be made (except for the homeownership programs 124). If you have a "bad" KFW interest rate, i.e. took out the loan 3 or more years ago, you could repay the KFW loan by special repayment with a normal annuity loan. This could save a few euros? Does anyone have experience? What needs to be considered? Are there issues due to the land charge entry?

Hello, I can only agree with nordi. Subordinated loans are offered with an unattractive interest surcharge or not at all... I can refinance completely :)

I can completely restructure my debt :)

You were lucky :) After consulting with my financing bank, it doesn't make much difference - so it's hardly worth it. In 3 years we will aim for a forward loan (+4 years) to repay the loan after the 10-year "lock-in" period. Let's see how the interest rates develop.