[dbaupp]

Note: despite the "VM" in the name LLVM is a native compiler: the rust compiler constructs the appropriate internal representation to LLVM and passes it to LLVM for optimisation and native code generation. There's not really a fundamental difference between this and writing the code generation step in pure Rust other than the latter missing out on all the benefits (speed, architecture support etc) of LLVM.

That is to say: there's not much difference for difficulty of developing new language features, but avoiding LLVM makes it harder to develop new fast language features.