Very good point!
Redhat is pushing LXC very hard these days. They do even have an Enterprise version called Red Hat Enterprise Linux Atomic Host, which is based on docker and LXC, IIRC.
Another important point is that RHEL7 and CentOS 7 have extensive support for LXC (using much more recent kernel as you mention). There is also templates for LXC:
https://github.com/lxc/lxc/tree/master/templates.
Being able to manage VMs with libvirt and friends (libvirt-lxc) will be of huge interest to many sysadmins who prefer cmd line
Is there really any cons to drop OpenVZ at all? I don't see any!
Can you re-use some code from HyperVM maybe?
EDIT: also, it might be good for Kloxo-MR to develop LXC support on a CentOS 7 to avoid using 2.6 branch of the Linux kernel
Still thinking better using OpenVZ or LXC. OpenVZ need special kernel but no for LXC.