I might sound like a complete idiot but in my experience the only difference between UE4 C++ and Unity C# is that the first one uses .h files. The syntax in both cases is so similar that you might think both are using the same language. In my defense: I am used to Python so everything that uses ā;ā as line terminators looks like the same language to me 
If you really hate header files - like I do - you could even keep the .cpp files empty and write all you code in the header file. Not that I would recommend doing that.
Support for other IDEs would be awesome. I just cannot get used to VS. It just feels like a bloated syntax highlighter.