Just to say it a different way, its always better to get an esc that is over rated for your application than not when you can afford it. But if you can't then at least make sure the esc has the minimum CONTINUOUS amps required for that motor. and the higher short burst amp rating of that same esc will save you in the event that something happens, like some weeds getting caught in the prop.

This is true for brushed motors and brushless.