Hello and thank you for Paint.NET. I get why you are using DirectWrite, but I still don't think that's the best approach to render fonts in paintings. The fonts look blurry and different than when rendered with Win32 (even with ClearType turned on). WPF was only using DirectWrite until .net 4.0 and when Microsoft released the beta of visual studio 2010 people got highly abused because of the blurred fonts on screen. So Microsoft introduced the "Display" font rendering option in WPF which mimics the windows ClearType font rendering pixel by pixel. Still, I think they didn't fix DirectWrite to support this mode. Scott Hanselman even mentions you in his article regarding WPF text rendering: http://www.hanselman.com/blog/WPFAndTextBlurrinessNowWithCompleteClarity.aspx
Here's a screenshot comparing Paint.Net and Paint in Windows 8.1
1. Paint.net
2. Paint
