I know this takes coding and coding is very scarce currently, etc., but...

Would it be possible to make partial shifts persist while shifted? NOT in the way that they do anything while in form, but in the way that if one reverts from form, they will have X partial shift up now that they are in humanoid form.

Simple solution to bring these spells into usefulness beyond level 20 and you might see some shifters revert and try some neat stuff.