Well as far as I know there are only great things with CSSU, you can change many things, just need to know what do you want. And honestly, I can't remember any negatives or harms to my device. But, you know, one will never know. And you might be the first :-) just kidding.
i updated my CSSU at work, and didn't lost anything. But it's totally up to you as usual. You are the one responsible for your action and mistakes. Take care.