Can't exactly give a precise statistical chance seeing as no one actually records this shit (idea.. maybe?) - It's also hard to determine seeing as different menus might use different methods.
Essentially though if you're extremely careful when it comes to mods, and dont make yourself stand out too much and use them for the slightest of advantages, as well as not freaking out when you're about to die and activating godmode etc etc, then you should be alright. I've used hacks since the 11zero11 menu from quite awhile ago now and I've not been banned yet.
I got pretty cocky at one point and regret it. It's a miracle I didn't get banned spawning shittons of Rhino's (tanks) for everyone to use.
Be careful/subtle with it and you really should be fine. Keep an open ear here on the forums for updates however seeing as if you simply stick a menu in and dont update it or whatnot you might get caught out inbetween updates of the game itself.
Hope this helps somewhat.
Edit: I'd also like to add that it would be a good idea to either back up files you're replacing with the menu's you're installing, or keep a list of names/original files on that main directory.
After installing a few menus myself and taking them out/replacing I've gotten lost in the files and broken my GTA a few times. I suggest you take a screenshot of the original file list so you know what should or shouldn't be there if anything goes wrong, or if you want to remove your menu(s).