I’d say the “buttery” is subtle but there, and I like that there is no chance of the distracting aftertaste you get with some oils.
I used to mainly bake oil cakes up until a few years ago when I discovered butter cakes, which I generally prefer the texture of. I haven’t baked an oil cake in the last several months just because I’ve been obsessed with Rose’s butter cake recipes I do love recipes like Fine Cooking’s Hot Chocolate Cake which uses both butter and oil. It calls for Canola oil, but I use Avocado.
I haven’t done it, but think that one nut butter can generally be substituted for another. With the natural nut butters you just have to make sure it’s stirred well to mix the oil back in, which leaves you less of that lovely oil to save. The other thing to consider might be checking to make sure they have somewhat comparable fat contents?