My JB Elephant-in-the-room is the awful performance. I'm complaining instead of having switched, since I haven't found anything and powerful for multi-file projects in Rust, and Python. I find myself, more and more, opening files in Sublime and managing the files manually when PyCharm+Rust Plugin is behaving especially badly. Restarting PyCharm often helps, short-term.
For Rust, any LSP-supporting editor with rust-analyzer should be giving a great experience. Not sure what you mean by "multi-file" projects, but RA handles a normal crate with multiple modules perfectly fine.
