What am I losing by not using the C# Dev Kit?

I exclusively use Visual Studio Code for editing code. I primarily work with Go, and a little bit with JavaScript/TypeScript, but I need to do some C# work.

I have no interest in using Microsoft's proprietary C# Dev Kit or dealing with their licensing terms. What capabilities am I losing? The marketing materials for the dev kit talk about a lot of stuff that appear to be features of the open source C# extension, so it's unclear which features are actually exclusive to the dev kit.