There are passworded branches available like the new 1.42RC that can only be joined using: Steam library => properties > Beta tab, enter password.
It would be nice to have option to download this side by side with the Dev branch(es) using game updater. Also ensure last stable branch is available.
Example of branch here:
https://twitter.com/Arma3official/status/581492639297572864
This change would mean comparisons between branches would be easier to accomplish due to being able to run separate versions. Compare code changes on functions etc. It would mean those tweaking mods could test out changes on the RC without compromising the integrity of the standard branch they edit in.
currently when using the betas tab to change to an RC version it will make the changes on the main install of Arma, I would like to have RC versions loaded separately to make comparisons easier to compare by being able to select the version I run.