CodeMirror vs. Ace

Here's why I went with CodeMirror over Ace for Rewritepad:

• Better support for textarea (good to have for scenarios where JavaScript is unavailable). Ace has a special build for it but it isn't compatible with the regular API yet.
• Smaller in size (34k vs. ~185k) and comes with a very handy compression helper.
• Much faster and deals with huge documents way better than Ace because it only puts the visible content in the DOM tree. As pointed out by Fabian Jakobs, the author of Ace, in a comment and by Marijn Haverbeke, the author of CodeMirror on Twitter, both CodeMirror and Ace use the same technique and in fact Ace actually pioneered it.
• Better documentation compared to Ace.
• Marijn Haverbeke.