This feature would be very welcome.
We have several managed firewalls and in the beginning of our setup, a few years ago, most firewalls were kept with the default "S1" virtual server name.
But now one of the managed firewalls needs a VPN connection to a large part of our managed firewalls. It's a total mess to move every virtual server to a different cluster and then move it back just to rename it.
Added bonus with this is that you need to move it to a cluster which is the same firmware version, otherwise it will mess things up and you can't move the server back to it's original location.
Please implement this feature, I saw it has been requested in 2011 already too.