I've been about 15 times and I consider myself intermediate/advanced and I have some Booters and they rock. My feet are wide and flat and I've had a tuff time finding boots that fit right and I noticed a huge difference my first day skiing with them but the main reason is because they FIT my feet perfectly. I got really lucky because I actually bought them from a fellow newschooler without trying them on first which is a huge gamble.
That doesn't have much significance to your skill. Realistically, anyone can go down "blacks" on their first day, as well as doing boxes. It's called having basic balance.
Also, where do you ski? Blacks at some mountains are blues or even greens at others.