Is it appropriate or inappropriate to use the nusach of the High Holy Days when davening on the days in between Rosh Hashanah and Yom Kippur? Because we put additions into the Amidah (Zokhreinu, etc) that are used in the Rosh Hashanah liturgy, I have heard people say these additions and their accompanying brachot using the melody from Rosh Hashanah.
This does not feel wrong to me. If that melody helps to remind you that we are in the Days of Awe and are being judged, there could be a positive benefit to it. I have never read anywhere that this is a recommended or even permissible practice though, and so while I have occasionally caught myself doing it, it may not be a good idea. Are there any sources that speak to whether this is appropriate, or at a minimum harmless?