There is another advantage to using a full script. Dialogue. Both before I started doing formal reviews, and was just doing spot reviews for people, and since I started doing formal reviews, I have yet to review a webcomic that had good dialogue. Acceptable, yes. Wooden, usually. But good dialogue that I feel like quoting later? No.
As much care should be taken with the words the characters say as with the drawing of them. In fact, I should be able to remove all the art from the page, leaving just the dialogue balloons and still be able to tell who is speaking, and not just because they are calling each other by name. The dialogue for EACH character should be as distinctive as their appearances.
And a full script is the way to accomplish this. Anyone who simply jots down the dialogue, and makes a few tweaks here and there is not putting the same care and work into the writing that they are putting into the art, and it is going to show. The script is the way to put that time, care, and work into the story, not just for the plot, theme, setting, conflict and the rest, but for the dialogue. If you write a line that is so generic that any of your characters could have said it, re-write it. I am not talking the Wolverine BS of putting the word "bub" in every sentence, but actually using distinctive speech patterns for your characters. If you wrote down sentences said by your friends, verbatim, you will find they have speech patterns, pauses, vocal tics, personal words, catch phrases, ums, and uhs that would let you pick out who said what.
Don't do any less for your characters, and to do that, put it in a word processor and play with it. The delete key is your eraser, and the keyboard is your pencil. This is a rough draft that you pull a finished script out of the same way you pull a finished page out of a rough sketch.
Let the full force of the personality of your characters come through in the dialogue. Write it out, and play with it, it is as exciting as the art work once you learn to do it.
Eagle
(and if it's not, see if you can find a writer)