That would mean 25% of €120k = €30k and thus exactly the same as the current program. The difference would be that you can also have it paid out in cash. It comes to the same then.. provided your BAFA application is approved
You are now talking about KfW 40 Plus, right?
The grant is usually (as the requirements of the EE-/NH-package are met) 25% of €150,000. That is then €37,500.
In addition, in the optimal case (when combining the new BEG funding and the old BAfA funding) 35% on the heat pump + possibly ventilation and KNX. On average probably around €10,000; maximum €17,500.
This makes a grant of €47,500 to €55,000 and thus €7,500 more than with the combination KfW 153 + BAfA.
Furthermore, there is an interest advantage, which I will leave out of the calculation, since you no longer have to take out the expensive KfW loan starting 01.07.