Well, if you own the domain you can point the MX record elsewhere if one host starts jerking you around. Of course you can have problems at the registrar level,

Well, if you own the domain you can point the MX record elsewhere if one host starts jerking you around. Of course you can have problems at the registrar level, but having used 100% self-hosted email, 100% hosted email (their domain) and hosted email pointed at by my domain, IME the hosted but my domain option is the most resilient.