I doubt the Ninja will be as nimble as your Multistrada. Meaning, you may have more difficulty beating out RPD in the slow races. Why not just put that money into your Duc? Assuming your selling or trading in the Multistrada.
I won't be test riding the Ninja 1000 or H2, as much as that sounds appealing. I've ridden with those in various settings. They're no faster than one of my newest ill-tuned $2,500 ZX9s, slower in the corners for sure. I've often fancied the ZX-10R, but it's too harsh of a ride for street and lacks sport-touring capabilities.
Let us know how the test rides go.