IE support is something really important to most users. especially with around 80% of the world still using it.
Raphael doesn’t seem that good, much worse than OnlyPaths SVG Renderer. But something that seems better is still Dojo.GFX
It supports Circles, Ellipses, Groups, Images, Lines, Draggable things, Paths, Points, Polylines, Rectangles, Text, Fonts, etc. and renders into VML, SVG and Silverlight.
It’s size isn’t too big either and there are CDNs for it. We could also learn from xDraw to design our editor.