Some reasons we have gotten behind TinyMCE
1. The code base is cleaner
2. After significant testing we have found the results of cut and paste from Word to be better in TinyMCE (compared with Xinha). This is important b/c most of our users cut and paste from Word (on Windows), which introduces a markup nightmare (save as html in MSWord to get a feel for it). Moving to TinyMCE is a first step in improving this issue. We hope to work on server side cleanup next, which might also help with the "attribute/tag not allowed" error messages that cause our users undue stress.
3. The demos (partially) support Safari, although we haven't gotten that to work yet
4. There is a company that is intimately familiar with the code it that offers support if we are in dire straits (the same company that released it under the LGPL)
5. The resizable window is cool
6. It does pretty much everything Xinha does...
7. and it scores better in accessibility tests
