As a person who uses Swift on both macOS (as a profession) and on Linux (for purposes of college thesis and contributing to open source) I have had really good experience using Sourcekit-LSP. I always use the latest release (and sometimes development) versions of the toolchan and I have been able to comfortably use Sourcekit-LSP via VSCode. I have been working on project using autogenerated code, that had more than 600.000 lines in total (taking to account parsed documentation). At this point, the stability of the LSP was at least comparable with my experiences on Xcode, where I have to restart or rebuild project on occasion too. My setup (complete with LLDB) consits of 3 vscode plugins.