It has nothing to do with "top heaviness", but with the fact that it does not have a clutch, so fine tuning the gas throttle and torque is almost impossible.
Doing tight turns, circles and eights as those on the motorcycle course is very difficult with cvt scooters.
It's not so bad really. Just hold on that back break and give her more throttle. You can also take a class and they'll put you on a little bike for the test. In fact a class would be a good idea if you are having trouble with slow speed stuff, they teach you how to do it and give you a bunch of pointers.
On the subject of top heavy, you should feel an MP3, 525+ lbs and that steering system has some weight. at least i can lock it when I'm at a standstill, but that doesn't help doing low speed stuff. One thing that helps is to look and focus where you expect to end up and not at your bike!
keep working that rear break the entire time and you'll get those circles down.