I am working on a project where at a certain moment I need to show for one month which days are still available. There is a function that calculates which days are available. My colleagues said:"Oh we know, you should return a BitVector32. That's the most efficient when working with a list of booleans." I would have used a List<bool> or something like that. A BitVector32 seems to me to be something for low level stuff when you are actually working with bits.
So, the question is. Should you use the BitVector32 whenever you need some list of booleans with less than 32 items or should you only use it for low level stuff?
Using a List is easily extensible to other time periods. Say you want to show two month at once. Oh that's bigger than 32. I need to change the return type and everywhere it's used. Great! And BitVector32 doesn't even implement IEnumerable<T>.
And unless it's in a tight loop readability and maintainability top efficiency. And the overhead of a list allocation isn't that big, unless you do it a million times per second.
So I agree with you that you should only use BitVector32 for low level code.