Security OpenVZ vs LXC

For years, I'm now using OpenVZ on my server, but support discontinued for Debian and Ubuntu, current releases seem to focus on LXC now, which is not a bad idea from the point of comfort.

But what about security? I remember I read once that LXC doesn't provide the same level of process and container separation than OpenVZ does. Unfortunately, I cant find the document anymore, but I agree there might be some security issues at least in the default configuration of LXC. For example, with a completely customized rootfs I managed once (in an older version of LXC) to change the host's terminal from an LXC container using chvt 1 and pressing Ctrl+C ended in a restart of my X11 environment when I tried to reproduce it today. I know, all container solutions use the same kernel and a kernel hack can lead to a container breakout, that's not what I ask. But it shouldn't be that easy to influence the host or other containers from a container.

How much security can I expect from OpenVZ and LXC?

My server exposes some guest ports to the internet, so I really care about this aspect, but I have to make a decision because the currently used tools need to be upgraded. Using LXC or similar is not an option since my server has a low-performance CPU.

PS: I'm speaking about the real OpenVZ implementation with vzctl 4.7.2-1. Some newer implementations of vzctl use LXC techniques.