These things have a ridiculous engine in them. I had a short 10 month relationship with mine. Terrible suspension and brakes, I should kept it and bought better brakes and suspension for it.
But man that engine...top speeds near 160mph, no kidding. That thing just screamed. And even new they didn't sell well so you could pick up a brand new one for $6500-7000 after letting them sit in the showroom for a couple years.
I did the Yoshi 3/4 TRC system (NLA now) and a power commander, but it wallowed like crazy in the turns and always spun the rear wheel if you even came close to the paint.
The only thing I'd change on my current Superduke is to give it the top end of an SV1000S.