Last one I bought was a Thill (balsa) .... the other 20 or so that I have were removed from trees, the shoreline, or floating in the lake. All but a few are slip floats. I think I've actually used one, once in the last decade or so, and that was before I had Livescope.
I keep one outfit rigged with a slip float (Thill Premium), but don't always take it along with me to the lake, unless I know I'm going to be using live bait.

And, yes, you are correct in your assumption that the weighted float is for extra casting distance. And you are also correct in thinking that it's useless for "lift bites" (which is why I don't have any of those types of floats).