The difference is that a RIP install resides in a folder and is not woven into the system. That is how I explain it to myself anyway. Using a RIP installation makes it possible to have multiple versions on the same pc. Also, as you noticed there are some versions that have not been merged with the master branch and there is no other way to run them.
As for stability, I have two machines running on RIP one of them is in a production environment in somebody else's shop. No problems whatsoever. I have been advised to remove the standard installed version when using RIP installations.
I use desktop launchers for RIP installs. Create an empty file in your config folder and put a bash script inside:
Code:
#!/bin/bash
cd /home/user/whereyourRIPinstalllives/src
source ../scripts/rip-environment
cd ..
linuxcnc ./configs/yourconfigfolder/yourinifile.ini
You will have to adjust the paths according to your situation. Then make the file executable (rightclick->properties).
Now you can point your launcher to this bash file so it runs it when you click on the icon.