Probably not a discussion worth having if your mind is made up[1], but I've found that FP actually forces me to hold a lot less in my head, rather than more. And when I say FP, I mean specifically impure FP (Clojure is what I have the most experience with), something that gives you the mutable state escape hatch without resorting to monads or other constructs designed to hide the state from you. The rest that you mentioned I can certainly do without.

[1] That said it's worked to my extreme advantage, so I can't help but throw it out there.