True, that is probably the reason why 2" is the hole size. It has been a while since I have bypassed a fence and it would be negligent to have something that worked as good as a ladder!

Normally you find an area that can be lifted up and you can expect barbed wire at the top, climbing is out the question though.

I would go for the bigger holes if it was my fence just so people don't vandalise it by lifting it or cutting the wire.