The biggest difference you will feel on a sportbike, aside from the riding postion hunching you over with your feet farther back than your used to, is that the bike is not agile at all unless your doing 80 mph. At low speeds, the narrow lock-to-lock angle and frontend geometry will take alot of practice to get used to.
And trusting your tires....

it don't feel right to crank a bike over that far and not stick your foot out. But you really don't want to do that on pavement.....
Take a spin on a 'standard' with a more upright riding position, with you feet under your azz, instead of up it. You might like it better, specially to learn the street on.
And cruisers..... well.....
