I think it depends on your content. I personally don't use scripts although I have in the past and did so extensively when I started out with my original channel. One day though I just couldn't be bothered with typing out a script. I'd sat down and said "right I want to talk about A, then B, then C, etc. I wrote these key points down and would normally use this as the starting point for a script. But yea I just couldn't be bothered typing it up. So I just went with it and it worked.
I think the key thing is to remember that everyone is different as to the amount they need to write. Remember having to do speeches during English classes? The people who took a whole script up there to read off of were the worst. They were dull and robotic and lost there place and struggled and it was awkward and horrible and they wanted to sink into the ground. The people who were the best had little cards with bullet points on to keep them on track, they were fluid and seemed more natural. As an example compare Bob Dylans recent 30-40 minute scripted speech with just about any politicians.
Finally I always consider scripts to be used for acting. Actors learn their lines and by definition aren't "real". They are faking whatever they are saying effectively. If you truly can relate to your subject then you wont need to fake it and you probably wont need a full script. Bullet points on a second monitor or on cards to keep you on track would be the way to go. But remember that's its your party and you can do what you want. Do whatever feels right for you.