Yeah, Bespin was trying a similar approach with regards to rendering. They had a lot more baggage (server side code, workarounds for issues that have now been resolved) that is no longer necessary. They've now merged into Ace though and the rendering approach was scrapped in favor of a DOM-based method. I think this gives it a lot more overhead than is necessary.
I'm going to be looking very carefully at Bespin, Ace, CodeMirror and Ymacs. Not sure which, if any, pieces I'll be able to reuse... especially since I'm hoping to move to webGL where appropriate. But I am not going to blindly rewrite pieces that need no such effort.
