On Debian Stable, I would like to be able to create a new instance of the OS, use apt-get to install some Unstable packages with dependencies, then cleanly delete the whole thing when I'm done. VirtualBox or QEMU would work, but Xen/KVM/LXC seem to be lighter and faster. How do they compare for this use?
Edit: To clarify, in this case, I want to set up to be able to install-use-remove dangerous things without messing up the base system. Looking for what would be most lightweight/fast.