I spent some time on running F# on Windows (8.1 professional), OSX (El Capitan) and Linux (Ubuntu 14.04.3). Bottom line, Windows is the best environment for F# coding.

• Windows with Visual Studio Community edition is the best.
  • ReSharper supports detection of F# NUnit tests, C# NUnit tests and C# xUnit tests (with extension). It does not support F# xUnit tests.
• Atom 1.2.3 with ionide-installer 1.3.0 did not work well on both OSX and Linux.
• Linux can use MonoDevelop, which is way better than Atom + ionide.
• OSX can use Xamarin Studio, which is variation of MonoDevelop.
  • xUnit.NET testing framework support add-in installs well on Xamarin Studio but not on MonoDevelop.
• Visual Studio Code is rather an editor than IDE. For debugging you need to run the app under debugging mode and then use Visual Studio Code to attach to the process.
• As long as you make the fsproj file to use .Net framework that is supported by Mono, the code is compilable on all three environments.