FOr me, if I write it down I will remember it and do not need to refer to my notes. But if I don't write it down I am likely to forget. So I did some testing and found that it isn't only the act of writing that helps me, it is quickly looking at what I have written. I think, for me, writing in my own words, and then reinforcing by going over what I have written, is the secret to remembering things.
As far as handwriting versus keyboarding, I find them to be equal in my case.
I'm in the same boat. In university, folks would ask how much I study to get good grades (20 years ago). I would write my notes and review them once or twice. When looking at the written word, I recall where I was sitting, what was going on in the environment, and often a lot (a lot a lot) of context that I would have otherwise forgotten had I not reviewed the note once or twice.
However, for myself, the keyboard creates some disconnect when reviewing notes. It's got to be hand written and, like mentioned, I usually only need to review it once or twice over the span of a week or two and then I'll retain the info. Lots of scaffolded and reinforced-by-association information.
> But if I don't write it down I am likely to forget.
Anecdotally, I have probably 4-5 full note books of scribbles and sketches as part of my project. It's not meant to look good or be finished thoughts, and I rarely look at old notes. So for me, the primary purpose is enriching the thinking process, so it's closer to the next step – prototyping. This lets me weed out flawed ideas earlier, so when I actually build something, I have higher confidence it'll work well.
I'm actually the opposite, I discovered very early in my college experience that taking notes just hindered my ability to retain the information (I guess because the process of writing and structuring my writing took attention away from listening.) So my undergraduate and masters was all done without notes at all.
As far as handwriting versus keyboarding, I find them to be equal in my case.