I added YUI a while back to oscurrency,primarily for the newsletter. It became disabled at some point, so I'm revisiting whether to add YUI back in or replace it with TinyMCE.
YUI seems to be whithering in support and while I used it for it's potential flexibility, I'm leaning more to scaling down an existing robust system as opposed to scaling up a simple system.
We primarily need rich text for the newsletter functionality. It can be added to profiles as well, but keep in mind how creative people can come up with creative font, color, size choices.
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Rich Vázquez