Another option would be to set up another account for the cfw ps3. When it does get banned (and you should assume that it will), you will not lose access to your primary account on the vita.
I've been lucky so far on my cfw console. Mostly I just use it for watching Netflix. Some online gaming, but not much.
I actually should follow my own advice and set up a different account for my ofw console. I've just been thinking about a console ban though, not an account ban.
As previously mentioned, the only safe way is to keep the cfw console off of psn.
I would much rather go to my grave not needing my gun, than go there wishing I had it.