I think that new stats would be difficult to logically place in the game without some sort of new system for upgrading them (think Cult of the Lamb- corresponding bosses and characters drop/give items that let you upgrade them). For example, perhaps the Wawsp Queen drops an item that lets you upgrade Spirit.
Viewing post in Stat System Overhaul (help me)
why not both? how about juice being a currency to buy goofy shit like rocket boots or a chainsaw or even a literal weaponized blender but to lvl up your stats you get puree for things you do and you can even convert juice to puree. maybee even boss seeds as like a sort of power gem to make them more tempting to fight.