I've recently upgraded routers, and have flashed the new with DDRWT. However, OpenVPN has started to release virtual appliances[0] which I can deploy directly to ESXI. Do you prefer OpenVPN or another solution? I think seperating the router / VPN daemon might prove more fruitful.

[0] https://openvpn.net/index.php/access-server/download-openvpn-as-vm.html