You've spectacularly missed the point.
Here's an example: Your site is stable and good, so you've set the TTL to something really long - say a month.
The various DNS places grab the record and store it nicely, requesting an update every month.
A while later, you need to change the DNS records. You set the TTL short, make the change, then set it high again.
However, you changed that TTL value shortly *after* one block of DNS updated using the old value. They don't know about the new TTL value or the new DNS records, so they will now wait one month to request an update.
Oh dear - now everyone using those nameservers can't find you for a month!
This scheme is proposing that when you make a change requiring new DNS records, instead of passively waiting for everyone to find out, instead you send out a cry of "Hey everyone - I have a new set of DNS records - come get it!"
And so they do - on your request.
If you haven't made a change, then the call is not sent.
Consider this "Push" DNS on top of the existing "Poll" DNS.
As to the behaviour of OpenDNS - well, that's another matter altogether. They have to make money somehow, so they use the NXDOMAINs to do so. If you don't like that, then pay someone else who does it the way you like.