In these modpacks when creating the worlds should you change the world type in options to BoP or will it not appear?
BoP is weird, it has it's own world generation type you can enable like you noticed, and it doesn't even limit everything it does to that world type.(last I checked, anyway)
I don't think you'll get many, if any, new biomes from BoP unless you use its world type, though, so if you like all the crazy Biomes it adds(and I certainly like some of them!), then you may want to use it's world generation choice.
Also, not a big deal, but there is a stickied thread for small questions like these. Helps cut down on needless threads, and some people even watch this whole sub-forum, so it helps them not get updated on new threads with just one small question.
Good question, perhaps not the best one for an actual thread.