I disagree. The core write-your-code experience is full of jank, to the point where I have wondered in the past whether the XS folks develop it in XS. Its smart indentation isn't smart (randomly indenting another three levels, not being smart enough to stick to the indent level I pick when I backspace to where I want it--next line, back out there again!) and occasionally the text widget will "lose" a line of text and take a few seconds to remember that it actually exists.

The Xamarin toolchain has steadily improved and its PCL support makes a lot of things a lot easier, but I can't envision a use case where I would want to do my development in their IDE. I keep a Windows machine just to have VS so I can do the 90% case there and suffer through the 10% in XS.