Mvvmcross includes a convert which translates a boolean into an MvxVisibility enumerable, and a target binding on each platform which translates an MvxVisibility to either a View.Visibility on Android, or an inverted boolean for UIView.Hidden on iOS.
Its usage requires to use a magic string ("Visibility") 2 times in the binding description. And it supports only boolean values in the viewmodel.
And last, it is distributed as a Mvvmcross plugin, which slows down the app's startup time, and crashes the app when the "link all" build option is activated", unless you add special code to prevent it. If you forget to add the plugin, it won't crash, it won't log, and you may search for your error a long time before remembering to add the plugin.