Multi-Domains v Domain Mapping - Advice?

I have one site set up as a Wordpress Multisite, carnaval.bz. I want to be able to set up another site, gatewaymanagementandrealty.com so that it is part of the carnaval.bz multsite network.

Looking at the options, I'm trying to determine whether it makes more sense to use the Multi-Domains or Domain Mapping Plugin tool to accomplish this. Advice?

Many thanks.