> multiple error variants that reference the same source error type which I always had issues with in `thiserror`.

Huh?

    #[derive(Debug, thiserror::Error)]
    enum CustomError {
        #[error("failed to open a: {0}")]
        A(std::io::Error),
        #[error("failed to open b: {0}")]
        B(std::io::Error),
    }
    
    fn main() -> Result<(), CustomError> {
        std::fs::read_to_string("a").map_err(CustomError::A)?;
        std::fs::read_to_string("b").map_err(CustomError::B)?;
        Ok(())
    }

If I understand correctly, the main feature of snafu is "merely" reducing the boilerplace when adding context:

    low_level_result.context(ErrorWithContextSnafu { context })?;
    // vs
    low_level_result.map_err(|err| ErrorWithContext { err, context })?;

But to me, the win seems to small to justify the added complexity.