This may be a daft question - I'm not sure.
I look after a good number of domains - 150 to 200.
No matter who the registar I have always pointed the domain's Nameservers at the server the hosting the website (and often the email). No idea why - just the way I always did it.
Commonly now the email gets hosted seperately from the website and I end up with MX records on a server that no longer hosts the email.
And as periodically I need to move domains from one server to another as they get old and full - I need to move the Namervers.
I 'm thinking its easier to leave the nameservers with the registar and set the A / MX records there.
Assuming hosts and registrars are equally reliable is either approach better than the other?