I've had servers hacked several times over the years. Fortunately, we've never lost anything of any consequence, but it's still a hassle in any case.

One of the things I like about NatNet is I worry a lot less about hacking now... not to say I don't still keep an eye out, but they seem to be really good about keeping security patches updated and keeping an eye out for unusual activity.

So far, at least, we haven't had any issues since moving to NatNet.