Have a look at the test results in ‘Learn’ for the YHDC c.t. If you’re using that, they’ll be a good guide. Otherwise, all I’d say is the errors will be smaller, but by how much is anyone’s guess.
emonLibCM will work down to below 1 second. All you need do is tell it the interval you want to use. If you download the zip file from EmonLibCM - Version 2.2.2, in it is the full documentation that gives details of all of the API.