Here are some thoughts on the development environment for the G3WGV FlexRadio Controller.
The controller is a BIG package! The compiled code comes to around 182kB, which, together with the considerable I/O requirements, means that only an Arduino Due will run this program.
It's also rather big for the Arduino integrated development environment (IDE), which is really more suited to small "learner" applications. Fortunately there are alternatives and I recommend the development environment that I have used more or less from the start.
It is based on Microsoft Visual Studio and the Visual Micro plug-in. These are available via the links below. Visual Studio is free and the Visual Micro plug is has a free trial period, after which is is just £29 for a three user licence. I wouldn't hesitate - the huge productivity advantages make the small cost seem cheap at the price.
You'll need to install the C compiler in Visual Studio before installing Visual Micro (it can be done afterwards but it's more hassle).