I print a couple of copies in TNR 12 single sp. to save paper while still making it readable, for the computer illiterate. I email the rest word docs as attachments. I like to get the edited copies back with the comments in baloons in the right margin. It makes it a lot easier to see what they are talking about.
Usually, I have to probe the betas with questions, like: Did you have a good picture of what the MC looked like in your head? Or, Did you ever get lost in the dialog, and not know who was speaking? The comments they volunteer are things like, "I really got into it, and couldn't put it down." Or, "You were right on in that scene with..."