Would it be possible to have a nightly build Rust compiler for convenience (faster build cycle, auto-update) and a dev version of Rust cloned from GitHub for experimentation
Try to configure your IDE. Though I am working on Windows computer, I think the idea is similar to Ubuntu.
First, I've installed 3 versions of Rust into:
C:\Rust\64 beta MSVC 1.9
C:\Rust\64 nightly MSVC 1.10
C:\Rust\64 stable MSVC 1.8
Then I configured my IDE (in this case, IntelliJ IDEA 2016 + Rust Plug-In) to use different versions of Rust depending on build selector.
After this I can compile my code with different Rust versions just by selecting build-config from toolbar.