As I started to read about pre-folds, it seems that they are the most economical and the longest lasting, as well as being a true "one-size-fits-all" option, because you fold them to fit your baby. When I was a kid, my mom used flat nappies, and I know how to fold them.
What else should I know about them? Are they a big pain in the butt? Do they leak like crazy? Are they generally not as absorbent? Or does that just depend on what they are made of? Or, does their performance mostly depend on what cover you put with them? Would you recommend getting some pre-folds/flats as well as some fitted nappies?

I imagine I must be driving you crazy with all my questions, but it's a big investment, as I'm sure you know, and I want to get it right! Thanks!