If you just want a deterrent - buy a blank box from ebay, preferably 2nd hand with a real
name on. Or buy a £99 Yale kit and sell the rest other than the bellbox.
My advice really is that simple, as there is no point having to maintain, install and support
essentially a rubbish system.
The cheap, nasty Chinese stuff is exactly as you say. I wouldn't trust it to guard a cat.
And as you say if someone still wants to break in, they will. That's my honest, genuine advice.