I strongly encourage everyone who wants to have some modicum of control over things, register your own domain and control the authoritative nameservers for it. It's fine to have route53 as an authoritative slave if you want. This lets you point the MX to another service provider rather quickly, such as in an instance where something has gone terribly wrong with your Google mail services.
control your own DNS. When you register a domain, your registrar asks you what you want to be the domain name servers for it. This is the same info that shows up for the namservers in a domain's WHOIS entry. If you control the nameservers you can quickly and easily do things like move the mail services elsewhere, in the event that your third-party-hosted mail services go rogue.
