Congrats on your VCE success, honour the work

Firstly, if I were you, I'd search up AN for this or look in the board where I've moved this thread to, there are heaps of topics that delve into this in great depth. Good resources to read.
That aside, as Russ said, it's ultimately up to you. Do you want to broaden your horizons for an extra two years or do you want to get straight into it?
Having now had four years of uni experience, I'd probably agree with Russ that graduate-entry medicine is a better pathway for
most students, it just gives them time to mature and explore uni life a bit better before hitting the rigors of med school. Having said that, it's not for everyone. Many people just want to get right into it, and don't want to fuss around with detailed knowledge about X, Y and Z that may not be directly related or may just be too detailed to be relevant to their practice as a doctor. There are people in my cohort who were ready to start at Monash at 16 years of age! There's really merit to both pathways and even with the worsening job market for doctors, 5 vs 7 years isn't a big deal.
Having said that, I know far too many people who had the same luxury as you (myself not included), and the vast majority chose Monash. I've never heard one of heard of one complaining and regretting the decision, they've all done fairly well in the coursework, and many (especially those from MHS) have risen to prominent leadership positions in not only the Monash med soc but also the Australia-wide one (a quick google of the 2009 dux will tell you what can be done!). From my cohort at MHS, 6 got the choice, 5 took Monash, if that means anything.
If it were me who had this opportunity, I'd probably still go to Monash. Not because of any profound academic reason (as I said, both sides have merits and they're probably about equal), but mainly because my year had 26 people who got in to the MBBS, and many were close pals, and I wouldn't be keen to ditch them or ever want them to be bossing me around on the wards as doctors more senior to me hahahaha.
Anyway, search and read those threads. Some users have written very long posts with pros and cons lists, should be helpful.