The biggest threat used to be bumping, until the scrotes discovered how easy it was to break the actual cylinder with a pair of molegrips. Now what you need is something to resist the breaking as most scrotes aren't going to have the skill or the time to pick the lock. On most euro cylinders they are easy to break as there isn't much metal due to the shape. So now you get sacrificial break of bits which are supposed to protect the lock but the scrotes can bypass that by driving a screw in and pulling the other non sacrificial bit out.
Various locks claim to prevent this but I don't see how a few lugs sticking out are going to stop it as there is nothing structural on the outside that they can act against other than the handle/plate and they are very vulnerable to a claw hammer or crowbar. You can buy security handles that are supposed to be tougher than the standard ones but I doubt if anything that mounts on a PVC door can be much tougher. Lets face it, most PVC doors don't even have the steel reinforcing fitted in the frame around the panels.
BTW as that prat keeps posting I miscounted the pins, there are nine in the ABS. I don't agree with anything else he has said as you can watch attacks on youtube and the pin inside a pin does take longer to pick.