I'm looking to add a few blocks of text that would only display for the master user. I see there is a class for isMasterUser( $user ). Would that be the best one to use?

On standard theme context use something like this:

if(zp_loggedin(ADMIN_RIGHTS) && $_zp_current_admin_obj->master) { … }

Within a function * $_zp_current_admin_obj* must be declared global if not already

Perfect. Thank you!