A suggestion (because I learned this the hard way...): If you can spare about 10GB of your hard disk it may be a good idea to create another (~10GB) partition on your disk and install another copy of Navigatrix in there. You can use this partition as a "laboratory environment" to try out beta versions without any risk to the integrity of your main installation. If something goes wrong you just re-install a blank NX into this play area.
The additional NX partition will just become another option in the boot manager's selection menu. It'll probably have the same name as your existing "main" NX but you can figure from the their position in the menu which is which. The
installation instructions in the Navigatrix documentation (step 3 onwards) might be enough to get you started if you choose to go down this path.