Mixed Ink: Does it work?

I read about Mixed Ink in the March/April Learning and Leading with Technology. Now, I've TRIED to use several real-time document sharing tools, such as Skrbl. I led an interesting fifth grade technology class one day in which we were all brainstorming ideas for a potential project with our partner class in Turkey. It did not go well. The site was overwhelmed with so many folks trying to log in at the same time so it was very slow and the entries went right on top of one another. It wasn't a disaster, but it didn't work the way I wanted it to. Mixed Ink supposedly does this better. It's like a google doc but more streamlined for collaborations between multiple parties. No invitations needed. What's different is that the group "rates" the best edits and the very best "version" is the one that is featured. It's free, but if you get the educator version, you get it ad-free and password protected. Otherwise it's very public. I'll letcha know how it works. Has anyone tried it?