I also have a Supersport (93). I won't say too much, but it really is worth exploring the aircooled, 2V Ducs. The hp numbers are not a good indicator of just how much fun they are to own and drive. They've got soul. I also had a 2002 Monster S. Fantastic bike. Fuel injected. Just hop on and go.
Don't get stuck with a plastic tank Ducati, and least not one from the mid 2000's. Depends on the model, but in the mid 2000's, they started using plastic tanks. These tanks are vulnerable to expansion issues because of the ethanol in our fuel here in the US. If was a big problem, with class action lawsuits involved. Javadog mentioned this above. Do your homework.
If had to go out and buy a liquid cooled Duc, and maintenance cost was concern, I guess I would lean towards a 749/999. Just my (admittedly somewhat unqualified) opinion. The 996 is widely regarded as one of the most, if not THE most beautiful bikes ever made. I had a 748S of the same genre. They are great to look at, and perform well, but (for me anyway) holy hell are they uncomfortable. Brutal riding position. They also suffered from insufficient chroming on the rocker arm rollers. If caught early, it could be solved, but if it wasn't and it started digging into the cams, throw your damn checkbook out the window. $$$.
Current steed:
