@kevin 0.6.0 isn't considered stable, so may introduce new issues that still require fixes. If you're only testing, then by all means use 0.6.0 to see how it performs, but if you're running an environment, and 0.6.0 doesn't work for you, you can't go back to 0.5.x. Your mileage will vary when it comes to using 0.6.0, support will usually only come from the devs, as I can't think of many other community reps that run latest in production.
Caveats, you may run into issues upgrading, read the errors, they'll tell you the issue (usually). Plugins that you currently use will need updating to the 0.6.0 versions (@latest) on npm, plugins you rely on may not yet be ported to 0.6.0.
If you're happy with all of those warnings:
In your nodebb folder.
git checkout master
If you've made any changes to core nodebb or it's themes, you may get an error at the git pull stage, you will need to handle those changes, either via a stash or merge. I personally use stash, as I run a relatively vanilla NodeBB.
Hope that helps.
This could probably be a life bible for everyone that is thinking of using Master, just replace the version numbers as required.