Running with DNSMadeEasy, is there a way to integrate it with Route 53 through AXFR to have two providers?
Looks like they are close to getting NOTIFY and IXFR (incremental AXFR) working. It's an interesting approach none-the-less.
Take a look at DynDNS's secondary service, that might work for you: http://dyn.com/dns/secondary-dns/