I do understand your concerns of elitism, but the hard truth is that nobody who maters views Macquarie as a "b rate university" and you will quickly come to realise this if you accept the offer. In my experience, the only people who make these claims are either a) HSC students with no industry experience or b) people with nothing else to fall back on but the "prestige" of their institution (which at an undergraduate level in Australia, simply doesn't exist).
Macquarie is very well known for its faculty of business & economics, especially in the areas of accounting and finance and many employers consider it on-par, if not better than that of USYD. This is coming from somebody who up until recently came from an accounting background at Macquarie and who's been successful in several job interviews with some pretty decent companies (not to sound up myself, but I am merely making a point). In fact, at the last interview I attended I was told that the BCOM/BAPPFIN sounded like a fantastic combination (not studying this anymore as I wanted to transfer into law). In other words, you will not be at a disadvantage to people coming from UNSW/USYD, especially being a double degree student and especially if you're actively involved in extra-curriculars and work experience.
The most important point I wanted to raise however, is that you're comparing two very different degree programs. A bachelor of economics is typically something you will study if you want to go down the road of being an economist (although your major will obviously be a large factor in this). A bachelor of commerce - professional accounting / bachelor of applied finance is as you said, a little more specialised. It will open doors in not just accounting and finance, but also in areas such as consulting, etc. What you're doing with this particular program is taking your standard bachelor of commerce with your stock standard majors in accounting/finance and splitting it into two specialised degrees, which puts you ahead of the normal commerce students.
The bachelor of commerce - professional accounting is a bit rigid in structure (meaning you don't get many electives), but the benefit is when combined with the bachelor of applied finance, you're automatically eligible for the post-grad qualifications you've mentioned.
In terms of international recognition, I would say that both would be recognised to some extent, but I would probably advise you to wait for somebody with actual experience in this area to comment.
At the end of the day, compromising what you've always wanted to study is silly in my opinion. Make sure you're studying exactly what you're passionate about.
Also, if you are considering driving to Macquarie you would need to be on campus before 8:45am to be able to grab a parking spot, since parking does get very chaotic after that.
Hope that helps.