Oh, I can tell you for myself that handwriting is awful. I'm focused entirely on the process of writing and can't think about anything else. When I type I feel like I can move at the speed of my brain.
I only take notes if I am trying to work out some of the things said or as support for this or that or maybe 2 really interesting lines or quips I want to remember just so later and I find particularly surprising or interesting (or mistaken, hah).
When solving math problems, yes, by all means take notes! I find writing with a pen indispensable because it's much more flexible and expressive. And i need the memory caching that writing provides.