Did you try doing native development with Xamarin? I do want to be clear that Xamarin.Forms is not Xamarin. It's a library that we built to help people quickly write very simple, data-entry style apps. That's why it's called "Forms." It's not intended to be highly performant or to replicate all the per-platform APIs in Xamarin.iOS and Xamarin.Android. For that, you should use the native APIs. We have a little more information about that here:
http://cdn1.xamarin.com/Architecture%20Selector.pdf
And the "What Xamarin approach is right for you?" section on the Xamarin.Forms page:
Before release, we had internally called Xamarin.Forms "duplo," to emphasize that it was for childishly-simple apps and screens, but we couldn't use that (trademarked) name for the release, unfortunately.
That said, of course we still want to address all the issues that you found with Forms. Would you mind dropping me an email - nat@xamarin.com?