I suppose I would like to know what it is about your winform application that made WPF not a good fit. We personally don't have any WPF in the shop, but have two Silverlight applications. The primary one has several hundred views. Between the Silverlight UI layer and all supporting services, etc, there's roughly 1.2 million lines of code. Personally I can't imagine writing it in HTML5/CSS/javascript. The loss of the power of XAML and the loss of strong typing all the UI code would make me cringe. Yes, XAML is a little more verbose than HTML, but crazy more powerful. Templates, binding, converters, etc. It's a markup language designed for building UIs, not a markup language for hyperlinking text. Whoever that it was a good idea to continue to dress up the pigs that are HTML and JavaScript have done our profession a huge disservice. Someone should have come along years ago and said, "Hey, in theory all of this web development stuff is great, but we need to start with a clean slate" and made the languages that we needed. Personally, I would love to see C# native development cross platform, and XAML as a choice for UI. As for WinForms, I've done my share. But, it seemed like significantly more work in WinForms to adopt patterns built for testing -- MVVM or MVC, dependency injection, etc. I did one WinForm app using PRISM back in the day, but it's no where near as elegant as what we could do in Silverlight.