All of my domains have the same NameServers: ns1.bule.org, ns2.bule.org… Bule.org is a domain name I registered in 2006, along bule.ro just because i liked how it sounds. I sold bule.ro to Orlando some time later, but kept the .org.
And moving from one hosting to another (dreamhost, imountain, mediatemple, synco and others), i found a .org domain to be very useful. First of all because the .ro domain management system sucks. Second, because it fails and it’s hard to update your nameservers when the system is so slow and it’s a pain in the ass when you try to move 20 or 30 blogs from one server to another.
So here’s how i work: i told everybody i host to set the same NameServers and now, when i move to another host, i just change the IPs from bule.org’s registrar for the NameServers. No need to change the NS for every domain name. No need to remember the passwords for every .ro domain or keep it in the mail.
I work the same, using the IntoVPS DNS service, wich makes the updates very fast.
Is more fast to move the domains from one server to other. I use afraid.org, and is very good because the update of the new server IP is changed in one second.