Speaking of RoboVM, sounds like it is making very good progress [1]. And can't beat its price of free.
LibGDX is using RoboVM these days instead of Xamarin, due to the price. Also anecdotally they found RoboVM runs even faster than Xamarin [2], despite being a young project.
[1]: http://blog.robovm.org/2014/03/robovm-0010-is-here.html