It isn't so much that more will drown it out, but more seems to dull and extend the effects. Harmalas do have a stoning effect on their own, which some people like, me included. So really it is personal preference. My preferred method is to smoke the harmalas sprinkled dry onto herbs and smoked in a regular pipe, then the GVG with only spice when I'm ready.
Herbs will help, but something like the GVG will make it taste nice all the time. It depends on the purity of your extract, but it can actually smell good.