John is right, that's the only reason, why you would like to show your own DNS, some providers call them 'vanity nameservers' because of that, as John said, less ram consuming, and less complicated things, using Interserver DNS is the best option.
In my case, when someone makes a who is to my website, I want to show my own DNS, insted where my vps is located. If you don't care about it, I don't find any other reason why you should not run Interserver DNS.
Thanks John, yeah, maybe I can help out or maybe get some answer in any case. Is good to know you have a forum!
Yes, I would save that too, best way to save ram avoiding own DNS, using interserver dns.