First off, thanks for discovering this forum, it is a great source of information and advice.
Secondly, you want a Ducati so obviously you have very good taste. Kudos to you.
When I was 16 I hadn't discovered bikes yet and I was into cars. My dad had an old 1966 Mustang that we rebuilt as good as we could on a limited (aka lower middle class) budget. My father was an airline mechanic and had worked on cars before that so he really knew how to build the motor, etc. His friend ran a body shop so once we had teh bodywork done he painted the car for a favor. The car was fast, stupid, scary fast. Everyone kept telling me it was too fast and I was going to kill myself. The thing was it was a 1966 Mustang that looked hot, sounded hot, and was hot. I had a huge reputation and never, ever, raced a single person... didn't have to.
I did lots of other stupid things that you do when your 16 - 17 but that will keep for another time. The fact is that when you are that age people can't always tell you what is best, you have to make some experiences of your own to learn from. Everyone on this board means well and has your best interest in their hearts & minds, even if it seem slike thay are talking down to you a bit. Just soak up the wisdom and then make up your own mind... it is the only way to learn and grow and become a better person/rider.
Now I am 31 and I own a coupe of Porsches and every ******* in a pick-up wants to race me at the stoplights. I simply laugh. I am secure in myself and actually do not care if I could win or not. I have enjoyed autocross, trackdays, etc. and know what my driving ability is and what I should and shouldn't do with the car. Of course like everyone I get suckered into showing off now and again. maybe I will jump off teh line, or book it to the next light, anyone who claims to have never done that is full of it. The difference is I don't actualy feel like I have anything to prove, I am just having a bit of fun and hopefully using good judgement when I do.
If you get the Ducati you won't have to prove yourself at every stoplight if you don't want to. Many people on this board own Monster 620s, 800s, etc. and can tell you that the general public assumes these are $20k race bikes and often simply back off when they see the Ducati name.
There is nothing wrong with wanting to know the performance of a bike vs. a car. If you have never owned a bike, how could you know? A 1500cc cruiser, can be slower than a 1000 standard, which can be slower than some 600 sport bikes. So the size of the motor, configuration of the motor (V, inline, Horizontally Opposed, etc.), and the type of bike (standard, cruiser, sports) all effect the bikes performance.
Any Monster will hold it's own with just about any car on the street. Take the Motorcycle Safety Foundation course as it will make you a faster, smoother, and safer rider. They are not preachy and will teach you things that will make you a better rider on any bike large and small.
If you decide to get the Duc please come back as the people are really helpful and informative and have great advice to give you. Who knows, we might all learn a thing or two from you as well.