We have been using TinyMCE since the 3.0 version and has been very happy with it.
The flexibility is superb, but most important the latest releases is very stable regarding to document editing.
But I see Channel 9 is using line breaks when pressing the enter key (force_linebreaks option in TinyMCE).
Regarding the TinyMCE team it is very experimental, and in my experience not stable when editing complex documents. I recomend that you test this option out before releasing. I left it a long time ago.
Aoccdrnig to a rscheearch at Cmabrigde Uinervtisy, it deosn't mttaer in waht oredr the ltteers
in a wrod are, the olny iprmoetnt tihng is taht the frist and lsat ltteer be at the rghit pclae.
The rset can be a taotl mses and you can sitll raed it wouth it bnieg a porbelm. Tihs is bcuseae
the huamn mnid deos not raed ervey lteter by istlef, butthe wrod as a wlohe.