If I create a MacOS VM, would it have the effect of doubling the draw on system resources?
Not at all a downside. The VM does add a slight performance penalty, but at idle, you don't do double work. Also, you can always quit apps on the host or the guest os to free up resources. For isolating changes and tests, VM are great. Especially igpf they support snapshots and cloning setups to avoid tedious configuration steps.